Mark,
I went "untethered" for years, my best advice is to shop for a system that dosn't "color" your sound too much. I used a Shure LX ( I think?) for quite a while because it seemed to give me about the same tone that I got when using a cable. Some systems muck up the tone to a point that you find yourself eq ing the crap out of your bass rig to get back what is lost. I don't have a real preference between VHF and UHF systems, but I do believe you should look for one that is "true diversity", basically two seperate transmitters and recivers, you'll get far fewer dropouts that way. Having said that, wireless technology is always improving ( cost down/features up ) but I havn't found a system that wasn't in the thousand plus range that I really liked the tone ( versus a cable that is ) Haven't looked in about a year or so, I'm sure they are out there.
FWIW,
Cheers,
Scott
PS..... I actually can't imagine
you playing without a wireless, seems like it woul cramp your style ( unless of course you could turn the cable into a fashion accessory
)