That baby is on my bucket list. I still remember watching Roy Clark playing a LP with P-90's. I was also a fan of SG Specials. Couldn't find one I liked, but I have a Hamer Special with P-90's, and it's fine.
I recently picked up a '56 reissue. This is my first experience with P-90's. I absolutely love them. I have other historics with a variety of humbuckers including Burstbuckers, Custombuckers, and SD Antiquities. They all sound great, but the P-90's have opened up a whole new sound for me that floats my boat! A tone revelation for me.