managing the wifi hardware requires a bunch of cpu cycles on top of the packet management. So I'd expect your wifi CPU saturation to be considerably lower than your wired CPU saturation... Still If you can handle 700Mbps wired, then I'd expect you to do 300 or 400 at least by WiFi...
Remember though that your WAN could receive 700 and then the queue on the wifi throws it away, but you still have to process the 700. That shouldn't happen for long periods, but it could spike like that.