I just received my third so called 'wireless' tether yesterday. Once I got the hang of connecting and disconnecting, I haven't had trouble. Knock on wood!
I don't know how well they will hold up as compared to a wired tether. I had one of the wired ones where the connector slowly wore and it would loosen ever so slightly going around curves and break contact. I had bought the loco used, and it had seen a lot of running.
I guess time will tell on the so called 'wireless'.