Hey I got a pair of these a while back..
I've got mixed emotions with them, I got a quad and I don't think they were anywhere near this expensive when I got them or I wouldn't have ordered them. Long story short, they sound great, but I don't know how much you can say they sound better than the regulars... Cryo treated pre amp tubes do seem to sound a bit richer and not as grainy.
On the flip side, 2 of the 4 of those power tubes have been giving me issues, one of them was bad when I got them and had to send it back, and the another of the duets is giving me issues, cracking and popping, had to take them out of my amp after they've blown a fuse a time or two.
My personal recommendation, don't bother with them, just get the regular SEDs.
Dallas