Dan – on one and spesh tyres work great tubeless. Chunky monkey isn’t great for my local stuff (which as you know, is similar to yours) – it’s not really what it’s designed for so I replaced it on the front of the 29er with a shorty (not big, but plenty bite) however the smorgasbord on the back is a good tyre, fast running and grippy enough to climb in sh1tty conditions too.
Chunky monkey on the front for big rocky stuff is ace, gives a nice feeling of reassurance when ye look down at it, and as said, great tubeless.
I used butcher and purg combo for years, I’d still go back to a purg (pearticularly the grid version) but the Butcher is a bit sketchy at times, it could do with a softer compound (which maybe exists now, I dunno).
Craig gave me a pair of tyres – purg and butcher – in 29, yer welcome to try them if ye want.