I just got a PRA WIC Wireless. Very sweet relatively new product. They have separate units for Guitar and Bass with an extended low frequency. Both transmitter and receiver are about the size of a small pager. They operate on rechargeable lithium ion batteries. Transmitter gets around 8 hours and receiver about 20 hours on a charge (USB charger included). Incredibly easy to use. I literally opened the box and had my guitar up and running wireless in about 30 seconds! The sound seems as good or better than any wireless I've used in the past. I used it a a gig Saturday evening with no problems. I didn't notice any difference in sound. And, with a 500 ft. range, it was great to walk out front and check the mix.
Joe Bob sez: two big thumbs up!
Bill, tgo