Look at the "Class" 1, 2 or 3 of the Bluetooth. Here's the wikipedia on that.
I bet you want Class 1.
Sony offers 2 kinds of wireless mics, Bluetooth and a FM frequency, other than the apperent difference what can i expect as far as quality, interference, how the quality fades over distance, or if line of sight nessasary, any of the user friendly aspects of eather of these mics would be very healpfull.
Thanks in Advance