Resurrecting the thread!
I own one, and a Mark V. I had a 5150ii with a recto 4x12 prior to downsizing to the 3 ( i wanted a small more portable head to move to practice) I also downsized from the 4x12 to a mesa openback widebody w/c90 (and a vertical 2x12, which is normally paired with the Mark V)
I've had no reliabiltiy issues, other than tubes and the knobs were screwed on to tight and the cracked off (so they send me replacements) Oddly i really started to dig the c90 cab with the 5150 3, but i would still like to get a GB style speaker for it. FWIW I use it to play VH style rock.. so naturally it works. Channel 2 is way better than the peavey's (crunch), I like the lead on the peavey a little better ( i used that as my crunch / ryhym channel) i may be the only person that like the "clean sound" that came from the peavey version.
overall i like the 3 more though.
Regarding the compression... well every modern amp is is compressed, most of them overly so, but thats the sound we like, or we'd all be playing JTM45/100's
To compare it to a mark V, sound not feature set, the mark is the typical tight metal (thrash) sound, a la metallica, dream theater, john sykes.. and the evh 5150 is more 80's marshall, maybe smoother less percussive. When i play VH on the Mark it never feels right.