Clonelord has made me think the New Men would make a great encounter for DH. It's mentioned they've been seeded amongst the imperium on various frontier worlds. Where they live in secret and carry forward their benefactor/creator's twisted version of the imperial truth.

It would be a good bait and switch for genestealer cults. Instead of a bunch of useful idiots being controlled by a bug you have a cult of genetic heretics who earnestly believe they are the inheritors of the galaxy and are the only way humanity will survive is by interbeeding with them. also I like the idea that the possible future where the chaos gods burn on a pyre of Bile's making is one where the New Men inherit the galaxy since they are warp resistant and fiercely fedora