I was actually just looking at the same setup! The extension is great because it adds another 1.5" of lift height (which i might need for my lifted yukon XL).
Another thing i was thinking about the quickjack is that its mobile... can use it in any of my garage bays, or the driveway.
Let me know how it works when you get it!
That was the other thing about it. I know I am not going to be in a shop. I would be under a carport for when it is raining but I can set it up in front of the carport on another uncovered area in the bright sunlight. That appeals to me and, I can take it elsewhere to use at a buddies house if need be. Hell, I will rent it out with a $500 deposit, only to friends that I trust and know that I own guns.