Double ditto on the J&S. Very stable. I tried the Sears yellow jack and I just didn't feel comfortable lifting my bike with it. Very shakey and very hard to find that sweet spot for lifting.
I have a J & S and my son has a Sears Yellow. They both do a great job. The Sears Yellow moves a bit. But no problem. The J & S does not move. It all up to how much you want to spend.
CW
Ditto on jack arms being too short, I took mine offand had my son add 2" to each, now I do not have to get down and see if it is equal on both sides. it sure makes it easier to lift and go...and oh yeah, I trust his welding...he's certified..
Now watch the video on this site and compare the two, it will be alot cheaper to buy this lift then it will be to buy replacement parts from HD to replace the ones that get dented when your bike falls off the sears jack. The J&S lift is just as good as the pitbull lift.