The slight movement changes are because they are actually moving (swaying in place). Hard to get precision shots from afar. After seeing these in game, I'd be fine with either SMIM or this mod, but one thing I'm positivity in agreement with Ess is that Better Bones has to go! It will be dropped regardless of the outcome of this mod's inclusion.
To get compares like these all you have to do is enter 'tcai' in the console to turn off the combat AI. Do this at the main menu before loading your saves. Then enemies will stop in place when you approach and sometimes get in a fighting stance, but never attack. If you're loading a save, they'll simply remain in place from the save. This makes it easier to take compares of enemy NPCs. I also spawned a couple of those skeletons to get more coverage.