I've never seen or heard of one. The closest thing I know of is the Fastrack Railer. I've always wondered who the target audience for this piece is.
I could understand it being an advantage for anyone with physical issues with their hands, such as significant shaking of any sort.
It's probably easier to get the trucks over the wider ramp and then let gravity do the detail work than to try to get both trucks on perfectly while at the track level.