I took the same set up as his and got very close to the shots I get with my machine and the same grinder. I think the smaller boiler in the Gaggia affects minimally the flavor over the extraction of a double shot (a less nuanced shot - we can be honest, right?) - if the barista is pulling single shots, then all bets are off - the best Barista will win every time.
PID a Gaggia, adjust the OPV pressure and watch good things happen paired with a decent (matters more than the machine IMHO) espresso grinder - I include the Preciso in this "decent" category - durability is my only concern with this grinder - not shot quality.
I picked my Silvano because I knew it would give the me the practical features of a home machine but with the adjustable parameters found on the only other machine I would consider for my kitchen - the dual boiler Vivaldi...
HX is great but I like the fact I have emptied my drip tray exactly twice since I purchased my machine this past fall - and it is close to empty right now - this would be a session worth of dumping for a consumer non-plumbed HX.