Kori, the problem with the usual single-lever height adjustment can't be overcome by using better aluminium. One solution that would work, is to use the same mounting mechanism on the front axle that is currently used on the back one: bolted-together axle pivots that have substantial bearing areas, and no vertical movement of the axle relative to the mower base. Just look at the back axle of a Honda, and imagine having an identical one on the front.
I don't think the guy in the video is achieving a whole lot there. If I were crazy enough to remove the back flap from my HRU195, I think it would mow that grass with a higher forward speed than he was achieving. Of course having only a 19" cutting width and no self-propulsion helps quite a bit.
