I also concur that you should be able to tailor the sound to your liking with this unit. I also found the Tung Sol 5687 or the Raytheon 5687 the best tubes for that slot. I'm running pinched waists in the 6922 slot and have stopped looking there, except for a a spare pair. Yes....the PQ's and SQ's can be as good, but for me the pinched waists had a little more of the harmonic overtones (cymbals, decay,etc.) I like.
It will depend on your preamp and rest of the system of course, but there are plenty of tubes to try out.