My experiences have been very good. I have the Kopförer about 6 months, they function properly and have a good for the price and the size of sound quality.
Only at the beginning some getting used to is the form, as the listener forward has a rubber attachment which anything goes in the ear, that feels strange at first, then very good because a great fit.
Maybe the higher priced handsets are even better, but I think this already very good.