Thank you for checking voltage consistency. That’s a nice detail not typically done.
I also read your grade mode test for NiMh with interest, because the Xtar VC4SL (aka VC4 Plus) is documented to have problems with consistency in charging NiMH. It doesn’t seem clear if it is due to using voltage termination, which is not reliable with NiMH batteries, or some other flaw:
Johnny_Bravo documented NiMH charge cycles ranging from termination at only 25% capacity up to not terminating until pushing 165% of capacity into the battery. Since the VC4SL charges at up to 1A, it is doubtful that the overcharging is benign, and the undercharging would be a nuisance.
Fortunately, your VC8S test showed better consistency at 103% to 109% of capacity.
As more people try out this charger, it will be helpful to the community if they can note if they see inconsistency in NiMH charging like the VC4SL, or if this charger is improved.