I am a big fan of the 45. It seems to do everything "just right"! Timbre, tonality, imaging and musicality are, IMO, spot on. The 45 does not have the mid range emphasis of a 300B, so more FR neutral. I tried some of the newly built 45 tubes, (Chinese and EML solid plate) but to my ears, nothing has bested vintage OS 45's. The European DHT power tubes, to me, seem to lean toward a solid state sonic signature, detail over tonality. Obviously, one must have highly efficient speakers to fully appreciate the flea watt tube.
Cheers,
Geary