Hi Craig and welcome to CS,Originally Posted by acdc link=1215582576/0#0 date=1215582575
My take would be that the steam pressure is more refined. In a Giotto premium/Rocket Giotto, you have a far larger volume of steam as the boiler is 6x the size of a Silvia boiler. Initial impressions from the Silvia boiler would be a smaller volume of steam at perhaps 4-6 bar. The initial steam is wet and unusable. The Giotto runs at more like 1.1 bar with a far larger volume of dry, usable steam.
There is no better milk texture wand IMHO than that of the Giotto and it is far easier to get perfect microfoam with a Giotto than with a Silvia. It is however possible with each machine.
The Giotto can be tweaked: http://coffeesnobs.com.au/YaBB.pl?num=1180142910. Site sponsors Talk Coffee and DiBartoli each have upgrade packs which endeavour to improve Giotto performance. The Giotto is nevertheless a brilliant machine straight out of the box and sells well for good reason. It is extremely popular with CSers. so you have chosen well.
Enjoy your new machine ;)