Regarding SS vs. tube rectification, either can be very good, or very mediocre. With tube rectifiers, everyone is a bit different ... Some people like being able to tune for sound by rolling tubes -- I hate it, and want things to sound good regardless. It bugs me that Sylvania 5U4GBs and RCA 5U4Gs sound best in my power amps, when I have a dozen Tungsols and GEs lying unused. I have another tube amp with solid state rectification, and it always sounds good. No characteristic "sound", as the power supply was properly designed around one set of SS diodes that will last forever. But, as Tom said, the design as a whole matters. If it is done well, the rectification shouldn't be an issue, just a design choice.
Regarding Scott's comment on 6922s, I have personally gotten some real bargains, allowing me to accumulate about 50 of 'em, 30 new-in-box, for not too much $$$. My biggest complaint with 6DJ8s and 6922s is noise -- knock one over and one channel is almost guaranteed to go. I find that the more expensive ones are even more likely to go noisy when knocked around. You can drop a 12AU7 from a couple feet, and it usually doesn't mind. But for conventional circuits, I'd generally rather listen to a 6922 over a 12AU7. The 12AU7's granduncle, the 6SN7, is technically a much better tube. It is easier to get very low distortion using a 6SN7, 6922, or 6N30P/6H30Pi (another great tube, IMHO!) than a 12AU7. But I don't want to get into any fights here...

Edit--as a further caveat, the circuit itself will make a bigger difference than the tubes themselves. Some of the least-linear 12A*7s, the 12AT7s, sound fantastic if you wrap a bunch of feedback around them (like in the Harman Kardon Citation I). The 12AU7 in a grounded-grid sounds nothing like a normal 12AU7 circuit. And, of course, 6DJ8/6922s sound terrible when oscillating, and the 6SN7 can even be made to sound bad if one tries hard enough
