Arms down to the sides might help you later on with posing, usually when 3dsmax was a thing, their default rig would be used as a base skeleton and you work around that & that would help you take it from zbrush to max and when creating a rig it would fit "perfectly", to the skeleton(biped). (typing this out i've never done that and seems like a brilliant idea, i remember reading someone doing it i think though in the past.)
Anyway nice i just think the arms should be at a different position, probably helps with critiques and comments to the anatomy. Looks like the concept.
