I don't think it would be that hard to regulate. Just ban all stringers from stocking poly strings. And if a stringer is caught stringing poly then he immediately gets kicked out of the tournament. And of course if a player is caught using poly in a match then it's automatic and immediate disqualification. I doubt many stringers or players would take that risk. Just have an official check all players' racquets before they walk out onto the court and have someone keep an eye in the stringing room.I would love to see poly banned or limited, but that would result in players using the closest thing they could right up to the edge. I think this would be a nightmare to regulate.