There's a guy in Pecos Texas who does this for weddings and other big parties. We ran across him at a graduation party for a friend getting a Masters. It was pretty good, but really seemed like a lot more show than substance. Pork has to be well done, and that's tough to do on this setup. He would shave some half cooked meat, then stir fry it before serving it to the guests. The marinade was good but I think it would have been as good cooked on a disc and a lot simpler.
He did not know what he was doing IMHO...
The best I've had was in East Los Angeles at King Taco. We would only venture down there during the day when the foot patrolman was on duty. Gang territory back then in the early 80s...
Anyway, theses $1 tacos were served on a small, double layered corn tortilla. There was the meat followed by finely chopped cabbage, finely chopped white onion/cilantro mix, a white Mexican cheese, and the optional searing red sauce. It was the type of bold flavor that would stay with you all day. Damn, I miss it.