I'm a valve amp user.having had solid states for years I will never go back to them. However, and it is a big however. My ampeg svt 2pro, when I got it second hand was the most unreliable piece of carp going. Stupid bypass safety cutout thing kicking in all over the shop, valves wearing out after 100 gigs or so, carp sound... Anyway. Had it rebuilt by a chap called Otto (sadly dead now) at the legendary rockfields studio and OH MY GOD! Cost 60 quid and I got back a working amp and a bag with about 100 components that he had replaced with top notch replacements. Consequence being it is reliable, sounds better than anything I have used and a set of valves lasts 3-4 times longer.
Another thing to note with valve amps. When a tranny goes pop it is usually finished (ime) but with the valve amps it often is not a big/expensive fix. Svt's are the muts nuts anyway, but after having it rebuilt the difference is ridiculous.