If you have intensive accesories such as an external HD, if you have it on usb 2.0 you notice the slowdown on your system, if you have it on firewire although a slower transfer rate it doesn't slow down your system because it is low profile.
I can see this wireless adapter causing probelms in big matches.
i can see all the hassle now of people wanting to play using the wifi adapter and the people with a wired setup not wanting them to join. then all the moaning when someone who has a wifi setup causes lag and ruins the game for everyone but refuses to beleive its him causing it.