I have a Gaggia Espresso on backorder. I questioning the machine for capacity. They say it has a 3oz boiler and the next one up is 6oz. How does all this affect the out come of shots or recovery time between shots. I'll be doing Americanos often as well as regular espressos. It's a $200 machine and the next is $300, is there reason one for the other.

Thanks

You didn't mentioned the other larger boiler espresso machine, but generally speaking, the thermal mass of the group and the responsiveness of the heating element / thermostat have more effect on the recovery and brew temperature for small boiler capacity machines like the Gaggia Espresso. If you're willing to modify the machine, a fairly easy experiment would be to turn copper tubing around the boiler to create a preheat loop. I bet it would make more difference than three more ounces of boiler capacity.

The other machine was a Gaggia also. I saw some items about preheating and such. As one who has worked on real boilers I have to take a different approach as it's not quite the same.

As far as I know, all Gaggias have the same boiler size, which is about 3.5 ounces. Could you be referring to a Silvia or Solis SL-70? Those have bigger boilers than Gaggias.

Generally speaking, a bigger boiler should translate into more stable brew temperatures and more steaming power. However, I've found that my Gaggia Classic makes a pretty respectable shot of espresso, and seems to be less finicky than Silvia despite the smaller boiler. It will run out of steam if you try to steam a large amount of milk, but you can trick the machine into keeping the heating element on by starting to steam before the ready light goes on. I do recommend upgrading the steam wand to a Silvia wand, however. It's a cheap and easy fix, and it makes microfoaming much easier.