Be wary (and weary) of dogma passed as learned knowledge - a Ford family car and a race car can both have a gas engine, but comparison between the two is more fruitful after lifting the hood to see what is going on inside. This blog generated out of a discussion on a coffee enthusiast forum where a post was presented that in my opinion dissmissed Thermoblocks without considering the application.
Is the HX better than a thermoblock only machine like a Krups? Sure it is. The steam thermoblock in the Silvano has it's basic operations in common with a Krups thermoblock since both heat water - I have seen both up close - the Krups (XP4000, XP4030, 964, 969) system is different in appearance than the one found in the Silvano - in the photo below on the left courtesy of a post by Chris from Chris Coffee you will find a large circle of metal under the word "bracket" - this is the steam thermoblock and is found behind the brass boiler inside the machine. On the right is the group assembly of the Krups. The Krups thermoblock is the part sitting above the polished metal group.
Most home use machines with a thermoblock will look similar but the Krups is nicer in build than some cheaper models I have dissected. These are required to hold a larger volume of water than the steam only thermoblock because this part functions as the entire boiler for the machine. Since the pump must still deliver 9 bar of water pressure, the cooler water from the tank will negatively affect water temperature stability while pulling the shot - hence the bad rap thermoblocks earn for brewing espresso. Make this block larger and the stability improves - ask it to flash boil only a small amount of water at a time for steaming and the design works very well.
Here is a cool video from Chris Coffee that speaks better than I can to the machine's ability:
And here is a longer overview of the Silvano - Steaming starts at 6:21 and is finished by 6:50 so less than 30 seconds to steam the milk - nice performance by this thermoblock steam heat bank.
/files/u2252/Silvano_vs_Krups_Thermoblock.jpg" width="500" height="211" align="bottom" />