The most modern candidates seem to have some concessions compared to mainstream-branded frames. Do these issues give anyone else reservations?

FM1002 Quirks.

• The bottom bracket drop is 20mm if I'm reading the geo chart correctlty. This is pretty high for a 29er. Maybe appropriate for a mullet?
• FM1002 kinematics are not progressive. Leverage curve is pretty flat (<10% progression) with a regressive section at bottom out. It seems like most mainstream brands have moved to a smoother, more progressive leverage curve.

AM831 Quirks.
Another recent frame that seemed promising, but has been plagued by design problems.

• The fork hit the frame in some sizes, so a spacer was needed under the fork.
• The first generation rear triangle was badly designed. If flexed badly, and bearing retention was an issue.
• A new rear triangle was released for the AM831 that may have solved problems with the v1 design, but more feedback from actual owners is needed to verify

I, too, would consider an aluminum frame, but it seems modern geometry aluminum frames just aren't lucrative enough to offer to the public. Carbon frames are the default mountain bike frames available. I've also seen a video about a bad injury sustained when a Chinese frame snapped under a rider. I guess the reputation of a frame matters.