From what I've heard about les paul neck joints it might make more sense getting the scalloping done on a guitar that's more playable in the upper register.

Dimarzio pickups are good if they fit your preference. I like them, but at the same time lots of people prefer their emgs, or Seymour Duncans, or Bare Knuckles, or whatever. It's more personal perference than anything else. Same with which pickup you use for solos, use whatever sounds best to you.