Xiamen far and x-bikes are actually reasonably accurate with their weights. They may have re-formatted their rims with improved braking surfaces though (with 1k/3k built in and ceramic/basalt braking track "improvements" <- errrrr.....Hmmmmm....
)....and they'll be slow to alter any weight penalty upward in the adverts, I'll bet. You have to ask a LOT of questions when dealing with the traders on alibaba to end up with a good purchase. It's not for the novice if you want a safe buy.
What I'd be more concerned about is durability.
Relevant info: weeweenieracer sprints HARD and is a bit of a demon on descents...he's "gear friendly" but wattage and braking hard (and late) are known wheel killers...he's 70(ish) kg. descents here=10-15% is NOT uncommon and repetitive switchback corners at 14-18% for 5+km is one of the climbs/descents his coach (yep...thats me!) will be putting in his programme more and more as time goes by. Heat deformable rims???....not a good call (he could use other wheels on those days tho).
He has access (or will) to appropriate sets of wheels for National level races etc so these will be his "weekend fun wheels"...he can train on his "whatever" wheels.
I'd consider a slightly thicker spoke for the "tension under drive" spokes that may have fractionally less stretch for the rear wheel DS (i.e. only 1/4 of them are beefed up) if using a more traditional assymetric hub or maybe even both DS and NDS under tension spokes if using the AC (as an AC rear is essentially a symetrical build on a shimano/sram wheel). If the rim IS available in 32 hole, perhaps the plethora of spokes makes this unnecessary?
You can use a rough guide of 4.5g per spoke and nipple as an estimation of adding/removing spokes (though the REVs he is planning on using are certainly light, they are a bite stretchier than your average spoke and respond well to reasonably high spoke tensions). Rim max tension is about 180kgf for this rim, I think so could be up towards it's upper end to get a decnt rear wheel built.
^Can any engineering wizzes give some suitable numbers or Legs11, ergott et al.....your thoughts please??? (re tensions).