The direction cue is "the tails follow," so that's simple. Direction might change the slip torque and does impact the noise made by the belt. They are a lot thicker than normal V-belts, so the interference issue makes sense. I ran them on my Atlas without issue for 3 years (ZAMAK pot metal) with no visible wear issues. A 3/4 hp lathe isn't what I would call a heavy duty application, so I can't speak as to whether the link belt performs like a normal belt under anything other than the light conditions on the Atlas. It was nice to be able to break and join the belt instead of pulling the spindle to change one.
I do know that the facilities/public works on base here like using link belts very much on pumps and HVAC systems. Part of that is one size fits vs. needing inventory, the other is easy install, but the take-home is that if they had a problem with them, they wouldn't be using them at all.