XVive U4 Monitor Wireless System

So we actually bought 3 of these sets for our church. They seemed to be a cheaper alternative to the regular wireless in-ear systems. The first one came with a defect from the factory on the connector. We returned it and received another one that worked well.
For the first few months they worked well but then one of the senders started to randomly select the channel by itself and although the channels were very rarely changed, the button to change the channel stopped working. You could not press it anymore. We returned it and it was fixed. A month later the 3rd set starting to show the same behavior with the channel button. It is very frustrating to not be able to rely on them. As a summary:
Pros:
- Great concept, works on 2.4 GHz so no interference from other microphones
- Good price

Cons:
- Button to switch the channel is very badly built
- Only mono, which makes creating a good in-ear mix very difficult.