I only ever play my J at rehearsal and gigs. I have a Franken-J at home for practice, but that likely won't see a rehearsal or gig until I do some more work on it, and then only if it sounds as good as my 75RI. (We'll see ... I refinished it and it looks damn good.)
Honestly, I've been GASsing for a Ric and for a nicer P, but now that I've got my rig squared away, I'm finding that I can get such a wide variety of tones from just my J that I almost don't even want to try anything else (lest I open up some major floodgates--well, if x other bass sounds good on my rig, what about y other bass ... or z other bass ... pretty soon I'm eating beans like a hobo and selling my body down at the bus terminal ...)
Ahem, anyway, when I finish building (stripping/staining, really) my FrankenSquier P, I think I'll bring that to shows for drop-d songs and as a backup.