I took a chance on the xvive U2 a couple of years back.
It is such a neat size, doesn't involve beltpacks or complicated set up. Literally, plug in and play. Battery time appears to be close on 5 hours, but I have never pushed it to its limit.
I would certainly recommend the U2, and I plan on buying another set, along with possibly trying out the U3 microphone wireless system.
It's suggested that there is a minimal latency, but it really must be minimal as it is not something that would effect a simple live set up in any way.