I ended up bumping into Bestie at the weekend.
If you’re reading this and still weighing up your options on the 29er I have found XT 30t, 11-46 works for me on 27.5 and 29, although it’ll obviously be heavy for less range compared to Eagle.
The other thing I didnt mention is I went for carbon wheels on the 29er. I think they pickup and track noticeably better than the Flows on the 27.5 bike. Fair enough the Flows haven’t had an easy life but if I had to choose between a better groupset and the carbon wheels I would go for the wheels every time.