Well, new GP-5 arrived and it's going back. No way can I get the midi control working with this one (well, I did a couple of times, but the it stoped). I tried two Chocolate Plus footswitches, both still set up from when I had the first GP-5 (which worked 100%).
Meh, ill give Tonex a go.
EDIT: User error. I forgot that the GP-5 needs to be powered via USB and not from a mains supply.