The Moxie was quoted as suiting 27.5, 27.5+ and 29, before I bought mine. I’m pretty sure. Now I think they’ve dropped the implication it suits traditional width 27.5.
My own experience was that with 2.6×27.5 tyres, 150mm 29er Pike and 165 cranks it was a shade too low, albeit I could adapt to it. Moving to a 29er front wheel, still both tyres 2.6, got the bb high enough to get me back to a normal frequency of pedal strikes (ie few, and due to my error). It’s probably still a very low BB but I like it as it is now.
I guess my front wheel change equates to about 8mm at the bb. If that’s right then the difference in Crank lengths is big in this context and I’d say even with 2.8s you wouldn’t want a much shorter fork or a much longer crank if running 27.5 F&R.
But assuming your setup plays OK with the bb drop, I think the Moxie is fabulous. I think it does retain some of the steel feel that I was skeptical burlier frames could (like other similar steel frames it weighs about 2.65kg IIRC), the finish is lovely and the geometry is exactly what I wanted. I love it.
I haven’t done any really long rides on it but I don’t see any reason it wouldn’t be comfortable for that, so long as you’re OK with its weight. Mine’s built up fairly light so I don’t see that as an issue.