Hi Phill,
PMK is my pyro of choice these days. PMK is getting quite low marks here and at other sites for staining. I don't have those issues. If the stain is great I can just print thru it. PMK is very budget wise also. It last for ever. I don't think that the BTZS tubes will affect the outcome. It will stain all it comes in contact with. I cleaned my bathroom sink with a powder called Comet. I would put the powder on the stain and let it sit for a while (like several hours) then I would wipe it up and everything would look good. This works with stains on porclean from selienum toner also. The results are definately "still effective" with a diffusion enlarger lamp.