I perfectly see that MDB_VL32 is the superior as a feature. On the other hand I'm a bit worried that it may hold up LMDB development for use cases you refer to as obsolete yourself.

While there are workarounds for this particular bug (which we applied), I wouldn't be surprised if MDB_VL32 still needs some stabilization after it will be officially released to get real exposure in the real world. Also, for future changes, the MDB_VL32 "fork" will have to be adjusted as well.