One thing to remember about the higher-frequency systems is that the range might be a little less. There's a lot of contributing factors to the range situation ands that's part of the equation.
I know a whole lot of folks use and swear by the inexpensive RF systems, but I'll never stop believing that "you get what you pay for" with RF gear. I spent a LOT of money on the system I have and use nearly every gig, but I can honestly say, I've never, ever experienced a drop-out or noise. And my RF system doesn't care if the basses are active or passive (good thing as I use both). I do (kinda) believe that really good RF performance can be had for less than what I spent ($2300 six years ago), but I'll do it again when the time comes. The sound of my bass coming through my IEMs via my wireless has been and will continue to be worth every stinkin' penny. I get around 5 hours of battery life with 2 AA batteries, but I use lithium rechargeables and I always change batteries after 3 hours, if the gig is that long. I bought 24 rechargables at the time I bought the bass RF (I use them in my wireless IEM rig, too) and in April of this year, I finally replaced that original set with a new set. So they waaaayyyyy more than paid for themselves.
I'm saying, check the ratings, see what pros are using, and save up for as much RF as you can afford (and of course, can justify, depending one how much you'll use RF).