The BBS01 is a centre bracket (Crank drive) replacement. It is very easy to fit (don't forget the extension lead for the speed sensor if twin rear wheel) and it works great.
As it drives the rear wheel there is no slip, on my wife's I do lift the wheel when cornering and for fun I ride it on two wheels, keeping the driven one on the deck. The wife and grandkids all love it. When we were in France on the Ile de Ré recently the number of people asking "where we rented" the trike was amazing, I'm surprised there is not more of a market for adult trikes.
I would go for one with the two wheels at the front and a single rear wheel as I think they are safer, a' la
Morgan. If you are near the channel tunnel give me a call, you can have a go on ours