I don't think they are trying to ban pellet grills from contests because of the flavor part, but because of the automation of it. Just fill the hopper and you are good for hours. I don't favor the BBQ Guru either, that to me also takes out the human factor for watching your fire and regulating your temp. For personal use, whatever floats your boat, but for a contest, it should be lump, hardwood, or briquetts. No propane, pellets, or electronics that control your pit.
I strictly use lump, hardwood, or briquetts when I smoke or grill. But, I know several people who have pellets cookers, and they love them, and I have tasted the food that came off of them and it was good. No complaints from me.