Bill, I can not offer a recommendation on the SMI braking unit yet. I have not had my system installed, but from what I read and from the recommendation of the local RV place, I am giving it a shot. I like the idea that it is not something you have to install and uninstall when using the toad. It all fits under the hood and is ready to go.
Maybe someone on the forum will have some experience with the unit.
p.s. -- I like your screen name. Barnacle Bill's is our favorite restrurant in St. Augustine, FL.