Thanks. This is good to know To be honest there's a wide variety in reviews of these units with a lot of people highly praising them. I've had a quick listen to the audio examples of this using a directly wired SM58 and SM58 with the wireless set and whilst I can hear some audio degradation and added hiss it doesn't sound as bad as some of the reviews stated!??
https://www.youtube.com/watch?v=gCgIhlSP6Oc&t=6s
It can be REALLY hard to convey audio quality looking at a video. For most people, if it passes audio, it's awesome. But when you do real side by side comparisons, that's when you realize how bad that audio might be.
Example, the Shure SLX has been a pretty popular mic. But, using it in a singing scenario, it sounds 'off'. Swapping the mic with a wired SM58 makes a pretty dramatic difference.
Again, many people may not recognize that difference until they can experience it first hand. I know I didn't. The differences in many cases are quite subtle.