It would be legal in Utah at 1000 watts, if you left it with the stock 20 mph limit. That's on the street. I'm surprised Bafang is not working harder on sophisticated shift sensors as part of the motor. In Turbo Bob's quick HD video, the shifts were pretty rough. Just compared to the European systems, Bafang is coming up a little short on refinements, as they up the power.
It's getting to be way too expensive if you don't need the power. If you did want all the power, I'd work very hard on the design of the bike to make sure it could handle it, and that the ride wouldn't put you on the list for a new kidney.