I would kind of agree with you there. The 5 is certainly more mellow than the 4, which can get quite aggressive. It still sounds like a good P though. I think the 4 sounds more like a bright 50’s Precision and the 5 a mellowed out 60’s Precision.
I have considered trying some other pickups in the 5 but overall am pretty happy with the sound, the 4 is absolutely perfect though😊