I bought a set of rearsets for my '05 Kawi ZX-6R because I got tired of shelling out for a complete OEM set any time the right side went down at any speed.
Sato and Gilles are among the favorites out there, but are incredibly pricey. Got my
OneSecondFaster rearsets for ~$225 (IIRC) and they're made entirely in the U.S. with U.S. machinery tools and materials. That was a big plus for me.
Install instructions were only fair as there is only 2-3 pictures, but they weren't overly complicated to understand. The finish is really nice on them and, of course, they're very adjustable. I haven't ridden on them to give feedback on flex yet but will do so once it warms up here.
I did have two issues on the install. One was that one of the holes wasn't tapped all the way through, though it was close enough for me to force the bolt through a few times which allowed it to be loose enough to get the bolt entirely through. Locktite, of course, is recommended for all fittings.
The other issue I had was that, following OSF's instructions, my shifter wouldn't move once the peg bolt (which pinches the shifter) was tightened to spec. Perhaps it was the cold of winter but I realized some 2 months later that removing one of the shims included and recommended for install resolved the problem, with only a very slight negative impact in side-to-side motion. I seriously doubt I'll ever note it with my foot.
In terms of customer communication, I was initially very unhappy because my initial request for help on the two aforementioned issues went completely unanswered. I figured out the first problem on my own but followed with a second email to them. Turns out their spam filter didn't like my Hotmail account and one of the guys happened to catch that some of their email was being incorrectly dumped. He was apologetic and helped immediately. I'm now quite satisfied with customer service there. In hindsight, I should've just called them.
During that email discourse Chris indicated they were looking at picking up a CNC lathe at which point pegs would drop to $10ea

This is why shims are currently included in the rearset purchase but the instructions need to be revised to indicate that one should only use as many as needed to provide a tight but operable fit. Obvious in hindsight