Played the P-bass with Chromes live for the first time at this evening's Ash Wednesday service at my church. First the pluses: it filled the church with the fattest bass sound I've ever been able to achieve, which was great in a full setting with 10-15 vocalists, Roland V-Drums, two acoustic guitarists and keyboards using a Fender Rhodes-like patch. The bass owned its own sonic space more so than it would have with my usual J-bass with rounds, and the D/G strings were much fuller-sounding than they are on the J. (However, by contrast, at services earlier in the day I used the J with keyboards as as the only other instrument, which worked well--I think the P would have been overkill there).
The P/flats bass also forced me to play more to serve the rhythm--I'm much more melodic with the J/rounds. To me that's neither good nor bad, just different in a way I liked this evening but wouldn't want to do all the time.
Biggest negatives were that I found it harder to control the dynamics when playing softly, and that when the keyboard player played with his left hand the sonic collision was almost head-splitting! Drummer gave me a *** look, but there was nothing I could do except weave in something an octave higher in spots.
That P/flats sound was enticing, but I think I'll stick with the J/rounds at church for the long haul. I may try the P with rounds to see if that's a good compromise--if I find that works then I'll just mod the J for parallel/series wiring to get the P sound when I want it, and sell the P.
Maybe try the J with flats. I actually found myself reaching to turn the tone knob down a bit. Filled the church like you said.