I have a pair of Line 6 G75: one lives in my rack for when I'm gigging the half stack, and the other one is in the floorboard of my smaller rig. Last time I checked, the G70/G75 generation were still the lowest latency of any consumer wireless.
The thing about the 2.4GHz-based systems is making sure other 2.4GHz gear isn't stepping on it. I use the G75's built-in frequency scanner at setup/sound check, and then again when the gig starts, and in 6-7 years of use I've never had any problems.
It needs a pair of AA batteries. I use the Eneloop rechargeables, bought two 4-packs years ago, and still using the same ones.