Not much cheaper overall if at all, but the availability of used 08+ rear calipers sucks. They are going for between 500-650 for the rear calipers when they do show up and then are gone instantly
You can get the 04-07 rears cheap at ~250-350, they look like crap, but I was going to powdercoat to match the fronts anyway. So total cost ends up being comparable.
KNS said they would take the bracket back if it didn't work. so I'm gonna go for it, I'll report my results.