I have had the SMI for 14 years and never had a problem, I do recomend the unit and will purchase another one in a heart beat.
I have the unit that has the vacum pump and is hooked to the brake booster, and is wired to the RV, one feature that I like is that I have small light in the cabin of the RV that indicates that the toads brake is activated.
SMI has my vote of comfidence, recomend it.
navegator