I realize I'm replying to a 3 year old thread, but I'm very curious if the original poster (or anyone else) in fact tried a different microphone and if there was an improvement. Also, while you were unhappy with your audio quality, what "Audio Quality" did you have set for your RRC-1258 units?
I noticed, a few days ago, my TX audio quality wasn't the best, but last night I realized this could be adjusted by the RRC-1258 "Audio Quality" settings. I switched from "0" to "2" and it seems to have improved. I will do more testing tonight, but I think I might have solved my problem.
Still though, I'd like to know other people's experiences with different microphones.
73 Marvin VE3VEE