With the server update speed, I find wifi to be a really unlikely issue, unless of course there's a problem with the wifi itself.
As a connection in general I can't see it being a factor when they run servers that don't even seem to update each 1/4 second.
I've played this without much noticeable difference on wired, wifi and even 4 frickin g (partial power outage, FC event needed to get done) and none of the latency seems to hold a candle to the server's overall performance.
However, crappy wifi is crappy wifi. I've lived in a place where wifi just got destroyed and I couldn't play much of anything on it and had to go wired. I'll agree users with wifi have that one more potential issue. Only potential, though.