Anyone have any preference / experience of using xt disc brakes or hope mono m4 old type
Cant make my mind up which ones to get.

I’ve had both and preferred the XT over Hopes. Hopes looked better but XT felt stronger, once set up never needed bleeding again and generally much more reliable.

Still running a set of Mono M4’s on my HT, plenty of stop and feel, bled once every few years.

Mostly about feel, this. Current XT has a more abrupt feel, which some folks like- feels powerful and instant. But others dislike- feels unsubtle and harder to meter.