I would be surprised of over-the-board cheating was viable in the long term. Seems like it should be relatively easy to stamp out provided there's a will to do so.
I've seen on the last thread that sometimes for cheating one bit of data is enough, something like a signal at some point where you could make a decisive move. I wonder, then, how you could send stealthily to someone a bit of data. Something like an implant under the skin giving a slight shock or vibration or heat. The answer to that would be to block signals from entering the space where the game is played, but then maybe you could implant a whole device in yourself to do that. I'm not sure how you could give it the data of the current game though.