Here are some reasons that you Father probably was reconsidering:

1 The channel has to be long enough to keep the roller engaged at all points in the suspension travel. When the suspension compresses, the channel now sticks down below the roller and the axle....can it hit the road?

2 With the required side to side play, there can be a noticeable "clunk" when the roller goes from side to side

3 The setup looks kind of clunky on a fenderless car; on a fendered car it doesnt show too bad

mike in tucson