Hey,

I've been using 6 cup chemex for the last couple of months.

I usually do 25/400, yielding a bit over 300g of coffee.

Is that something a 3 cup model does better?

I think the 3 cup would technically be better for that size brew. Because it has less glass it will probably suck less heat out of the brew bed. But, if you are enjoying the taste of your coffee from the 6 cup, I probably wouldn't bother spending money. Idk, it's hard to say. Over the years I've acquired a ton of brew gear, and I've had lot of fun brewing with different methods, but nowadays 95% of it lives in a closet. If I were in your shoes I would probably get a Kalita Wave instead of another Chemex. My go-to home brew is on a Kalita Wave 155; 15g coffee to 250g h2o.

I can't find kalita locally, so I don't wanna bother with ordering just kalita online. How about V60? They are a lot cheaper than chemex and should be very capable?

Has anyone tried doing lower volumes (15g of coffee or so) in a 6 (or 8/10) chemex? If so, how do you like it?

I haven't tried, but 15 grams of coffee in the 6/8/10/12 cup Chemex filter paper would probably not fill up much of the bottom of the filter and make it harder to do a good pour-over. I have a 3 cup Chemex which I use occasionally (along with the Kalita 155/185 and December Dripper) and I also have a very large Chemex, either 10 or 12 cup so not much middle ground Chemex wise. Most of my Chemexes have come from thrift stores so I end up with whatever I find, not necessarily the size I was looking for.

I'd thought I'd heard that the 3 cup Chemex was harder to use, but I haven't noticed this. I've also used the 3 Cup Chemex as a coffee server on occasion when brewing with another method and splitting cups.

The Kalita paper filters can be hard to find sometimes, and a bit costly, but I use them in both the December Dripper and my Kalitas and have been happy with them.

I really like chemex, but I haven't tried V60 to be honest. The reason I bought chemex over V60 in the first place was because I really liked how it looked.

Those two are, unlike kalita, available locally which makes filters shopping a lot less complicated.

I may have to get a 3 cup for times when I just want to "taste" some coffee. What is the minimal amount you can make optimally in the 3 cup?

The cone on the 3 cup is much longer and narrower, not sure the angle of the 3 cup versus the 6 cup, etc. It should be able to go down to 15 grams, though, without much trouble. I have a V60, but don't really use it, I find it harder to get a good cup in the V60 versus the Chemex or Kalita brewers. The following thread mentions that standard filters can be folded to fit the 3 cup as well.

Chemex - Which is the 'Optimal' Size

If the Kalita is a no-go, I would also recommend a plastic V60 01. They are usually very affordable. They typically require a little more user technique than a Kalita, but with practice they can yield sweet and delicious mugs of coffee. As far as a recipe, a good place to start is Google search "Vimeo Matt Perger V60". The benefit of the plastic V60 is that it's cheaper, won't break if you drop or knock it, and plastic won't suck nearly as much heat out of the brew bed as ceramic or glass would. A gooseneck kettle would be necessary to help with consistency from cup to cup. But if you don't have or want a gooseneck kettle, then Clever Dripper or AeroPress is going to be your best friend.

I have a gooseneck (hario buono). I'll try to source the plastic V60 locally, just to try it out if nothing else. It's cheap (glass/ceramic, while a lot cheaper than chemex, isn't cheap if never used). Filters aren't a problem with V60, many places carry them.

An update;
I got a ceramic 02 V60

First impressions? It's pretty similar to chemex brewing wise, maybe a little more sensitive because of the thinner filter.
It's got more body and less acidity, perfect for more chocolatey coffees.
Do I prefer it over the chemex? I don't think so. They both make amazing coffee, but I kinda like a cleaner cup that chemex produces. It's all good though, my significant other prefers it to chemex .

I used 20g/320g for both, adjusting only the grind and keeping technique the same (3:45 brew time, same stirring, pouring...).
The barista from local specialty cafe said that 3 cup chemex is more of a "joke" and it's more of an aesthetics thing.