As for your concerns of the bike falling off. After you have raised it, there are tie down loops on the jack for straps. They work good. Don't try to strap it down while it on the floor, because the tie-down loops and the bike change their relative position to each other when it is raised. I built my first one about twice as big as the on pictured and put a piece of diamond plate on it and a section of channel steel on top of that. Now I can roll any bike up on the channel and set the side or center stand on the diamond plate and lift the whole thing up to 28 inches. I used an 8 ton bottle jack. I've lifted my HD dresser, about 1000 lbs, no problem. and after it's up and strapped you can roll it all over the shop. The one I built has out riggers on each side, with adjustable pads so I can climb up on the bike while it's lifted, without fear of tipping.
The problem with this type, pictured bike lift is, the two rails that the bike actually rest on need to be under the frame and most scooter have plastic covering the frame or as Mr. Paul said, engine and belt housing where you need to lift. De dee, you'd be better served to spring for the lift table at HF tools for $429. It is item # 68892 it has a 1,000 lb capacity and lifts up to 29 and 1/2 inches.