Re: SP90-1 (P-90) vs SPH90-1 (Phat Cat)
P-Rails won't be an exact P90 replica. That said, I love the P-Rails neck. I've had SP90-1, -2, Phat Cats, and P-Rails in the neck of my Tele and the P-Rails was the best choice for me. I never could get along with any of them in the bridge, though. I didn't do any mag swaps, so I may have to revisit that at some point.
The P90 sound of the P-Rails is just a great sound. P90 purists will say it's not a P90 - I don't care. It sounds awesome. Plus, I can go full humbucking at the flip of a switch when I want a thicker tone.
I've never had a huge issue with P90 hum, but I find the P-Rails to be a little quieter than the SP90-1/-2 were.
If you do decide to go P90, you can't go wrong with either the -1 or -2, imo. I liked the -2 a little more because I like neck pickups to have some heat. Again, if I had been into mag swapping when I was testing them out, I would have tried another combo in the -1, just to add another dimension. If you get a P90 and want to try a mag swap at some point, search these forums for blueman's descriptions of the various mag combos in P90s.