What Jimmy said...plus there's the option of adding a high output humbucking J at the bridge that actually has a chance of approaching the output level of that P pickup. Most P/J configs I've tried (and I've tried many) are not all that useful in live gig situations because the bridge pup always sounds weak compared to the neck pup and you can never balance them.
Drop a hot J pickup in there, or a preamp, and you get a lot of really usable tone options.
A girl asked me what bass players do in the band since there's already a guitarist. I said "You know how cheerleaders do that human pyramid thing? Well, we're the fat chicks on the bottom."