I have a homemade set that my brother built when he worked at a structural steel shop. Mine are HEAVY duty I can barely move the ramps one at a time and the stands are about 80# each. My brother moved down south and didn't want to lug these monsters with him so I got it. It is perfect for pulling a trans, brake lines, drive shafts, etc. and nice just to get under and check things over. Mine put the bottom of the tires about 20" off the floor and adding the normal ground clearance I can almost sit up under the vehicle. I can't use a "real" lift in my shop due to ceiling height so these are the next best thing. I leave them on the floor (off the stands) and just drive my '41 Ford truck on them. I really like them.
My problem was finding a way to get the car that high but 31V sorted that out. The wheel stands are a great idea and I can make those all day long. That gives me an idea for a tall jackstand that can be used under the frame so the wheels can come off.
The concept is great, but as an old steelfitter ,the channel type wheel tracks have almost NO strength with the side angles turned up like that !!! Hence the sag ???
some might use have use for it, some might not. friend had bought one of the ones that have been on the market for years. the limited height was OK for small jobs like oil changes. only place he could leave them set up was in garage. so, parked one of his rides on it, front up and rear down. after a while the rear seal on trans started leaking. ramps ended up beside his house and not used.