I use the Samson Airline bass wireless with my Series I / S II electronics 5 string and some of my other basses, I haven't had any noticeable problems.
I don't always use a wireless, depending on the size of the venue, and I do prefer a wire but its nice to be mobile.
I would try to find out what touring bassists are using, I would imagine whatever brand some of them use, it should be reliable.
Sennheiser and AKG have been around along time, they make quality gear.
I have good experiences with AKG microphones.
I guess it depends on your budget too
(Message edited by beelee on December 14, 2005)