Some horses tolerate it, others not so much. Been using one for 4 years, love how easy it is to clean and take care of (got enough to do, if I can cut back my work load I will). That said some horses react badly to it, thats usually when I switch to my handy fleece girth kept hanging in the tack room.
I do not like the waffle pattern neoprene, had one and it DID rub my main trail horse raw, but the "solid" ones work just fine and have never bothered her. Waffle pads also rub her though, so I think she is one of the horses who doesn't react well to waffle patterned tack. I have a weaver neoprene cinch right now, and so far it is standing up pretty well, hasn't sored anyone up and has a nice "clench" to it while still being flexiable so my mare has no constriction to her breathing.
Hope that review helps.