If you want something a bit different, you may want to try the Mesa STR445 which is the JJ6L6 tube. Mesa is now offering JJ and Tung Sol tubes in the power tube line up, all tested and certified by Mesa. Check out their online store on the Mesa website.
I have not tried any of the new offerings or from Eurotubes in the Roadster. I have run =C=6L6GC, =C=EL34, Gold lion KT77 but that is about it. Felt the EL34 seemed to take away too much for me with the Roadster, could because of its darker tone. I should try the other tubes again now than I have revamped the preamp section. I do have some EHX 6CA7 I should try. I did run a pair of Siemens el34 STR450 with a pair of the stock STR 447 EL34 in the Multi-Watt dual rec, that sounded interesting. The Siemens tube (NOS Mesa STR450) sound basically the same as the standard Mesa EL34 STR447 but smoother, not harsh. I though those worked much better in the Royal Atlantic but for me the NOS =C= EL34 (Mesa STR442) is more enjoyable in the Royal. Sorry for the other amp references as this is not being helpful.