Not sure if it's been mentioned.. but the GS/3 uses a saturated group, while the Linea Mini uses a combo group/boiler. I've heard of saturated groups having a different mouthfeel.. I've never tasted a non saturated group shot right next to a saturated group shot, so I'm not sure if this is true.

If I was going to buy a GS/3 (and money was no object), I would only buy it for the looks. I think the GS/3 MP, especially with custom side panels and paddles, is one sexy machine. In a home setting, they probably deliver very similar espresso quality. After all, it is a La Marzocco, and they wouldn't have their name on it if it didn't produce LM quality espresso over and over again.

Generally speaking this is a thermoblock:

http://blog.seattlecoffeegear.com/2012/ ... ermoblock/

This is the LMLM brew boiler:

http://bwissue.com/ecmgrnt/117686

It's still a boiler. You can trace the piping to see where water leaves the boiler, passes a 3-way, and returns to feed the brew environment. You can also see the absence of an in-boiler heating element. It has a lot more in common with a BDB or DC group than it does a regular thermoblock based brew group

"Saturated" groups aren't a special thing. The coffee in your PF doesn't know it your group is saturated or not. It just experience a dispersion patter, pressure profile, temprature profile, and brew environment geometry. The benefit of saturated groups is a stable and consistent temprature profile. The standing pressure inside may also effect the natural pressure profile.

LMLM is definitely not a thermoblock.

It is a radical departure for La Marzocco from the saturated group design in their commercial and GS/3 lines. Here's a more technical overview by someone more qualified than me. He speculates that this integrated boiler design may well wind up in the commercial applications too.

http://coffeemachinist.com.au/linea-mini/

Here's a video of a test of its recovery and temperature stability, which is quite remarkable.

https://www.youtube.com/watch?v=XB7_vApkX9k

I think the GS/3 has some advantages in a working setting. The ergonomics of the GS/3 seem better suited to production throughput. Everything is open vertically and there's more workspace.

On the other hand, the LMLM, is 2-inches narrower, which in a domestic kitchen, is a big deal. I don't want to eat up counter top space. But the work space is less open, the steam wand and so on, aren't as ergo for throughput. Nothing, "wrong" with it, but if you're zipping through a lot of single-serving steaming milk pitchers and pulls, you'd probably appreciate the extra 2-inches and the open-air GS/3.

On the steaming side, the LMLM seems to have amazing ability to steam. So much so, that I bought a tip from Slayer with smaller holes. The LMLM comes with a "burn me" steam wand, which is offered as an upgrade kit for older GS/3 and as an option on the GS/3 instead of the no-burn arm. Honestly, in the home, I'd prefer the no-burn arm, even if it did restrict steaming a bit.