I've taken 1 of my neighbors for a ride last weekend. He's around 250 pounds. A big guy.
It took me aprox 1 minute to get used to the difference in behavior of the combination but after that it was just like driving around with an empty tub. I did change the suspension set-up after a few miles, because the sidecar tire would hit the fender on every speed bump. The adjustment system works like a dream, it took me just a minute or 2 to change the set-up on the side of the road.