I know this is a very old thread, but I wanted to post my experiences regarding tube rolling.
I picked up a 350EXR off usaudiomart that came with Sylvania 12AT7WA tubes with green lettering. They are very dynamic and musical with good highs and lows, and a very nice midrange that presents the soundstage a bit more forward than I'm used to. For all previous tube gear I had been running the re-issue Genalex Gold Lion tubes. Gear that I have used the Genalex tubes with are Decware CSP2+, TAD 150 Signature and Doge 8. Since I had a spare set of Genalex I installed them into the 350EXR thinking they would better the Sylvania 12AT7WA. I think the Genalex 12AT7's that I installed into the 350EXR must be bad because the soundstage shrank and moved back a bit behind the speakers. Additionally, the bass was really lightweight compared to what I'm used to with the Genalex. The decrease in bass was as if the speakers were hooked up out of phase. Double-checking the speaker cables confirmed they were wired properly.
I'm considering ordering another pair of Genalex Gold Lion 12AT7 to see if the spare tubes have simply gone bad. Overall I'm really happy with the amp, though the heatsink fins on the back of the unit do get extremely warm. I'd estimate they're over 130° F.
Equipment = NAD M51 --> Doge 8 (4x Genalex 12AT7) --> 350EXR (2x Sylvania 12AT7WA) --> PMC OB1