Re: If SD59n suits my guitar...will the Custom 5, too?
It's an extremely scooped pickup. I had one in my Les Paul years back and just could never vibe with it, it has a lot of bass and treble, but the mids were non existent and it made the pickup sound pretty harsh. I ended up using a regular Custom instead, it sounds much fuller and matches the 59n very well. Alternatively, I've also tried the 59b in a few guitars, and it's extremely versatile, you can get a lot of crunch from it if you're only playing up to some heavy rock/even some hair-metal styled stuff.
I have no experience with it, (so take this with a grain of salt) but just from listening to clips I'd love to try the 59/Custom Hybrid, that sounds perfect for what you'd want in a pickup.