I use wireless because my DAC is on the opposite wall from my computer and there is no easy way to run ethernet cable. My wireless receiver operates on 5GHz band since 2.4GHz is polluted and has only 3 non-overlapping channels (1,6,11). I also found out that my microwave operates on one of the channels causing dropouts. In addition 5GHz has advantage of poor wall penetration, shielding my room from outside signals and has 24 non-overlapping channels.
So, in either case you transmit data and not the music (no timing attached). WiFi needs receiver and it might produce some amount of jitter. My receiver (Airport Express) produces about 280ps of it. It should be kept below about 50ps (to be inaudible) by either using jitter suppressing DAC (my Benchmark DAC3) or reclocker. There is also possibility of router generated electrical noise to couple into the gear, but you most likely have router working anyway. Ethernet could also inject noise, but is probably a better solution. You have also option of asynchronous USB, that also delivers data in packets and might inject noise as well. But again, injected noise might be non-issue. You have to try for yourself.
