5150 or XXX ???

I haven't been a big fan of what I've heard of the Triple X. The only time I've liked it is for the rhythm guitars on Nickelback's 'The Long Road' album, and even then it was mixed in with a Triple Recto.
 
xxx is a great sounding amp but i wouldnt swap my 5150 for anything.
recorded with both and xxx is a bit tighter and clearer sounding but 5150 has the thick crushing tone we all love it for.
If u find the 5150 is getting muddy beyond 4 (although that is v v loud!) then eq can be tweaked to fix that, turn resonance down a bit etc.
And those active eq's on xxx r a bit of a pain in the arse, tweaking has to be really slight and carefull, 5150 is pretty much fool proof! which i like.
 
Apperantly theres an mod for the XXX which makes the "chuggachugga" unlike anything else on the market, and folkesson(famous swedish amp-modder) claims that this amp gets the most aggressive tones out of all amp mods he does(which is quite alot.).
Ive never used the 5150 or the XXX myself, but ive heard clips of this mod and it sounds brutal! But maybe you should stick with the "safe card" and keep your 5150, like everyone else says. ;)

Edit:
By the way! The XXX has a noisegate built in, that you cant adjust, which probably is what annoys people, folkesson claims the gate kills the crunch in the amp.