A guy I just did a frame for has this set-up on his bike. It's pretty nice but way too much $$$'s for a cheap guy like me. A few years ago we did a seat/shock set like that one and used two $20 mountain bike shocks and replaced the springs with some cut down 5" seat springs. That bike was in the Horse a while back, the rust colored bobber with the ugly sheepskin seat. I don't remember if any of the pics showed the seat/shock set up but I do remember it was the most comfortable hardtail I ever rode.
The nice thing about a kit like this is pretty much everything is ready to go; a little welding, bolt on the shocks, and off you go. When you're cheap and lazy like me it can take weeks of scrounging and fabbing to get it done.