I think that as described this Titan Air Jack is pretty nifty, far and beyond -- light years in fact -- better than the wimpy jack that came with my R. On even the slightest incline the stock jack is a tad dangerous. I guess I should really look for another one -- but the jacks I've seen appear to take up a lot of room.
In short, the Titan Air Jack is an air bag inflated by attaching a hose to your exhaust pipe or to an air compressor. You can change two tires in one go.
Anywhoo, my only questions are: cost, warranty, weight and deflated volume.