Yeah, they just seem stable in both control and footprint.
I actually had a look online at these air bag jacks last night after reading this, and found the main factor when looking to buy one is the height limit. The cheaper ones tend to top-out at about 300mm, whereas the ones closer to £1k and up, give you about 500mm. Also, they will only slide under motors higher than about 140mm, which is fine for our trucks, but no good for most cars.
I read online of one model reaching it's limit in 25 seconds. Maybe some are faster, but that seems nice, steady and controlled.
Although, I think you could be right, JDO, I think the good old bottle jack still wins this category for a few reasons right now!
Na, don't do that yourself, best take it to the garage.