My AxeFX rig lives in a stack of rack cases that sit next to our drummer (contains our IEM system and laptop for tracks, click, midi, etc). Wireless is almost a necessity for me simply due to the location of my rig. Makes for a clean stage though. We don't have any racks, amps or cabs on the backline, just pedalboards (MFC for me, AX8 for our second guitar player).
I was using an X2 XDR95 (predecessor to the Relay G90) and had absolutely no issues. We started playing a song where our singer would play an acoustic guitar and I'd play a bass, both routed through the AxeFX simultaneously, and I got tired of having wireless for myself, but having to run a lead for the acoustic. This led me to ditch the X2 and pick up 2 Relay G55s (basically the G90 tech in a half-rack). I was worried about this because my X2 ran in the 900mhz band, but the Relay runs on the 2.4ghz band. Even in venues with tons of interference, I've experienced very few dropouts. Granted, I've never had dropouts with the X2, but I was impressed with the performance of the relay. Just scanning through the channels and picking the one with least interference seems to work well enough for me.
I have both my wireless units mounted in the back of my rack. The main input goes to the front input of the axefx. I do this so that I can just unplug the wireless and plug in a cable if I need to instead of having to change the settings in the axefx menus. It's much faster in case of emergency. The second unit goes into input 2 on the back of the axe. I also have the balanced output of the first unit going into the rear input 1 for redundancy, but it's not actually being used at the moment.
From what I understand, the Axe 3 can automatically switch between the rear input and the front input if it detects a cable in the front input, which is super cool and would prevent the need to run the wireless output to the front panel (for emergencies)
