I'm something like unto a short scale land baron so I've got both. The TMB30 pickups are fairly bright so they don't do the vintage tone thing as well as they do modern tones, and I use vintage tones a lot. For that reason I put D'addario tapes on the Talman and now I feel much better about the way it sounds. A $60 Dimarzio Model P pup would be a big improvement I think.
I'm not a fan of the toggle switch on the Mustang PJ. I would prefer more of a 75% P, 25% J tone overall, so I pretty much just solo the P pup. The stock strings that come on the Mustang are very thin sounding and like several other individuals in various threads, my volume drops when I dial back the tone knob.
IMHO, as they come from the factory, the Mustang PJ is a better overall bass but at 30% of the Mustang street price the TMB-30 is a far better value for the dollar. The quality, to my eyes, ears, and fingers is close on both.
Neither sounds as good to my ears for classic rock than my Gibson SG but I realize that them's fightin' words in some sectors. It's just one man's opinion, that's all, and TB is full of opinions...