I would not use the go pros 2.4 wifi while flying the G using the transmitter control signal also on 2.4 wifi.
You may get by with it until one sad day when the transmitter hops frequency directly conflicting with the transmitter.
Why risk it? Use a little more camera battery and sift thru a little more footage and keep yourself from the agony of watching your copter fly off on its own uncontrollable.
I personally saw an older phantom do this and my friend told me it happened to him with his older phantom.
If you like to watch the progress of technology it seems dedicated cameras are the way of the future. (Phantom 3 and 4's and inspire 1/2 have migrated away from go pros and use their own dedicated cameras)