A reversed P is more balanced sounding. On a normal P bass, as you play across the strings, the E-A strings sound different from the D-G strings. When you reverse the two coils, the D-G strings are fuller sounding, and the E-A strings are a little higher sounding, so they blend together better.
IMO that's the way fender should have done it. But back then they wanted the treble strings to be brighter, and bass strings to be deeper. They also angled their pickups on Teles and Strats, and as with the P bass, those guitars sound better with the pickup angled the other way.
On a Strat, the treble strings get very thin and screechy on the treble pickup. Part of these reason why Fenders and G&L guitars are so bright is that Leo was hard of hearing. He made the Musicman guitars so bright that no one bought them!
I did that - sorta - on a 'Mirrored-Precision' that I made last Summer:::
It has some of the nicest balance and a great piano-like clarity that just rings pure. There's also a nice 'burp' to it to with the right blend.
All-in-all, I've enjoyed this design a lot.