P in the bridge is awesome. If you love precision tone and punch but wish that you could dial in some more attack and bite, do this. I have a P/J, J/J, and P/P. The P/J is very versatile. The J/J does the growly pissed off J bass thing and the smooth treble roll off J bass thing. The P/P is by far the most powerful, has the most punch, and sits in a rock mix like no other. With my setup, its just as versatile as the Jazz but doesn't sound anything like it.
The P/P is passive and has volume, volume, master tone, varitone, and varitone blend. I highly recommend doing this as you can instantly get a smoother vintage tone or an aggressive sound. I strung it with chrome flats and am wondering what on earth I was thinking before. I dial the neck full on for normal p tone, and then dial the bridge in about 75-80% and have the most unbelievably powerful sound right now. If I favor the bridge I can get a completely unique woody sound.
My band plays with a truly excellent group about twice a month. Their bassist is extremely proficient and plays an American Deluxe Jazz, also strung with chromes. He tried my P/P through his rig last week and was blown away enough to go out and buy out a P to do the same mod to this weekend.
I couldn't be happier with this bass.