It will definitely be interesting to hear different tube complements (and compare at some point when my BA comes back from Craig.)  Too bad I only have one TS BGRP as that's the only 6SN7 that I may prefer (for my listening tastes) to the mullards.  It's also a hassle finding some new PX4's as someone trashed my last pair.  I kept trying to listen to the gear but all too often found myself listening to the music.  That's a very good sign.