I've heard that the Uniden's have some problems decoding the control channel data specifically from an EDACS system. I had one and at times, when monitoring an EDACS system, it wouldn't immediately switch to the right voice channel. It did work properly most of the time, but at times after the user depressed his radio key, I would just hear 3 beeps and then the channel would clear. Does the GRE PSR 500 have the same problems as I just described?