I'm getting ready to purchase a used IEM system and I need some concrete advice on which frequencies to stay away from. I live in the US and I know the 698-806MHZ is no good. Are there any others that may become "bad" in the future? Also, can I operate below the 698-806 with a system that uses 614-647MHZ? Any help or references would be appreciated. Thanks.
-Eric
-Eric