I have the Rocketfish wireless product installed. It's sending the sound to two rear 5Bs. Setup was simple and it works fine.
The only issue is when you set up your AVR. Although my 5Bs are rougly 8 feet from my listening position my Yamaha AVR saw them as being close to 20 feet because of the lag. With the distance set property (I just went with what my AVR was happy with) I haven't had a problem and you'd never know they were wireless.
The Rocketfish (BestBuy's brand) is the only one I tried. I gave them a try before I spend a fortune trying to get wiring back there and figured that I'd just return if it didn't work out. Give them a try but save the receipt just in case.
Joe
If you can't have fun doing it, it's probably not worth doing.