I didn't install the whole wiring and switching that's nesseccary for all 4 P-Rails modes (Rails / P90 / serial / parallel), but I did install a push-pull for P90 / serial humbucker.
This thing rocks! As a humbucker it's an output monster, while as a P90 it growls and bites. Edge doesn't use it but he doesn't need a versatile guitar - he just gets one for every single sound he desires.
The only unexpected Problem was the size. The P-Rails is deeper than the Burstbucker, so I had to extract and bend the metal piece that holds the pickup. But in the end it turned out fine, and thanks to some soft foam rubber it's now exactly parallel to the strings.
The wiring is Gibson standard, by the way. I bought it unwired, so I went for the original layout instead of the killswitch.

Alex