I'm a relative newbie to this, I've had the Izzo Alex for nearly two months now. I was considering a Dual Boiler, but in the end, I decided DB vs HX wasn't the vital factor for me at all and I went for a machine with E61, rotary pump and seemingly good build quality. I've got the non-plumbed version and I find the HX with the reservoir easy to use.
One thing that did put me off the DB a little was the fact that the brew boiler water would be sitting for a while and I'd prefer fresher water.
Flushing the HX is straight forward and there is plently of good info about that on this site. I've only been using one bean blend the entire time, so I've got a HX when I don't need to hit various brew temps, but that isn't any problem at all. From what I've read, you still have to flush the Brewtus to bring the group up to temp, rather than cool the brew water with the HX type.
After using the pourover machine for a couple of months, I can really see the convenience and advantages of plumbing them in, while filling the reservoir and emptying the drip tray isn't much work, it'd certainly be much handier if it were all plumbed in, and I'd still have fresh brew water running through the HX, but I can't plumb in my current location.
I'm in Ireland and got my machine from the UK, so I can't comment on your vendor situation.

mrgnomer wrote:It's hard to go by opinions, though. The usual bias is to promote the equipment you've got.

I'm happy with my Alex and wouldn't swap it for a Brewtus

Let me make an attempt to summarize what I (think I've) learned here:

$1500-$1600 price range choices/advantages. Models in the range: Andreja Premium; Vetrano; Alex; others (a tricked out Anita with a new steam wand, p-stat and thermometer will get close to the range). The points listed below do not include shared traits (steam power, E61, etc.).

HX
Pros:

• water: fresher water that doesn't pick up any boiler residue
  flexible: easier to change temps for different experiments / switching coffees
  quiet: rotary pump available in pourover model (Alex) for quiet operation

Cons:

• Hard: temperature management requires experience, experimentation, and (exacting?) routines that, for example, require you to grind & tamp in a specific amount of time to pull the shot before the water is too hot again

Brewtus (only model in range)
Pros:

• Easy: stable, almost fire and forget temperature management (flush a couple of ounces solely to warm grouphead)

Cons:

• water: boiler water
  not quiet: vibe pump is much louder (only applies vs. rotary HX)
  less flexible: delay when changing temperatures

If you lower the budget by 200, then you eliminate the only double boiler (Brewtus) and steaming becomes the big separator between HX machines and single boiler but very stable machines like PID Alexia. If you raise the budget by $300+ to get the features of the double boiler Mini Vivaldi, then price becomes the separator.

Thanks, folks, for helping me figure out the key pros & cons of machines at the same rough price point. I am still undecided, I must admit. Quiet morning operation is seductive, but aren't grinders loud anyway? I know my current MDF would wake the dead.

Note re plumb-in v. pourover; not a huge issue for me. I have very nice new granite & a slate wall on the exposed walls of my kitchen that I will not drill through, and pulling filtered water from the fridge is not a big deal for me. (It's not on the list of things that I mind right now, and I go through a lot of water with Carezza's tiny boiler & tiny reservoir.)

Bex wrote:HX
Cons:

• Hard: temperature management requires experience, experimentation, and (exacting?) routines that, for example, require you to grind & tamp in a specific amount of time to pull the shot before the water is too hot again

To me, your HX Con is a minor issue. There are some very good guides on this website that explain the whole thing in detail (Managing the Temperature of HX Espresso Machines). I thought it was a bit daunting at first, and that was the main reason why I was looking into DB, but the more I read about HX flushing, the simpler it seemed.
And as regards timing, I find that to be minor too. I'm very slow with the entire process and with very little experience I can conveniently flush a bit, build my basket at a leisurely pace, then flush & go. And that first flush is only if the machine has been idle for a long time, otherwise I can just flush & go. It really is a lot easier than it might sound

neilCC wrote:It really is a lot easier than it might sound

I hope so , but I can only compare the two in this way.

Bex wrote:HX
Cons:

• Hard: temperature management requires experience, experimentation, and (exacting?) routines that, for example, require you to grind & tamp in a specific amount of time to pull the shot before the water is too hot again

Even with group digital thermometer adapter this is true IMO. However true, not that difficult to master depending on the person. However, much more of a hassle always having to surf for every shot all the time every time.

Cons:
Brewtus (only model in range)

• delay when changing temperatures

Miniscule delay. Lowering temp after changing setting just flush a bit to cool brew boiler down and go. Raising temp a few seconds to a minute or two to raise temp depending on raise factor then quick flush as usual to stabilize group temp.

FWIW I've had my HX Bric' over two years. Temp management is a cinch for reliable spot on shot temps. That said someday will likely upgrade to DB at home. But not until some new models come to market.

I'm sorry, but it is threads like this that have made me realize why Brewtus and other double boiler owners have simply declined to comment on these issues in droves. Here we have a group of HX owners commenting on machines that they have never used and don't own, and passing the dis-information along as if they are stating facts.

The thing that bugs me the most is this belief in "stale water." If you use bottled Crystal Geyser, is that water stale? Is the water held in the pipes in your house stale? The water does not get stale in a double boiler. Period. If you are making coffee, you do not have stale water. I can attest to that considering that I have to re-fill my reservoir at least twice a week. This is just a ridiculous statement that has to go.

Have you ever burned yourself on the supposedly cold e61 grouphead on a Brewtus? I have. The group head stays hot, ALL DAY LONG. If you feel that you need to flush, all you have to do is fill your cup with water from the grouphead and it is up to temperature.

Delays in temperature change? All I have to do is prep my portafilter and the temperature is ready for me to brew. It takes no longer than a couple of minutes for the temperature change to take effect.

And what is the deal about the vibe pump? Silvia has a vibe pump, but no one seems to complain about that. The only benefit the rotary pump has is noise reduction. It does not have anything to do with the results in the cup. It does not make better espresso. My grinders are noisier than my Brewtus!

If you really want to know about double boilers, you should go to the user's forums for Brewtus and Vivaldi. You will get real information from real owners, not HX owners with opinions.

Sorry! I know I'm ranting, but I'm tired of this.

Randii wrote:I'm sorry, but it is threads like this that have made me realize why Brewtus and other double boiler owners have simply declined to comment on these issues in droves. Here we have a group of HX owners commenting on machines that they have never used and don't own, and passing the dis-information along as if they are stating facts.

Often true enough. Glad I don't qualify as a target of the rant! While I don't own a Brewtus or Vivaldi but have HX Bric' at home, I have used both and do own a 3 group PID'd Linea.

Randii wrote:The thing that bugs me the most is this belief in "stale water." If you use bottled Crystal Geyser, is that water stale? Is the water held in the pipes in your house stale? The water does not get stale in a double boiler. Period. If you are making coffee, you do not have stale water. I can attest to that considering that I have to re-fill my reservoir at least twice a week. This is just a ridiculous statement that has to go.

Good to hear from the Brewtus owners, too!

So, leaving aside "staleness," which perhaps is a bad word, is it true that boilers will generate deposits over time, and it's harder to clean the insides of them, so there is at least some advantage in water that comes directly from the reservoir to the coffee? Like the HX flush, the extent to which this matters may not be relevant at all....but it is true?

BTW, I happen to believe in what Lewis Black jokes about - that our bottled water obsession has "ruined water." I just filter at the fridge and go.