Like I've said before,
The folks at Pro-Circuit have THE relationship with Kawi and they've figured out just about EVEYTHING on the KX500. Jim "Bones" Bacon is a KX500 GURU...on top of that...he's in-charge of suspension.
The neat thing about P/C is that they make the geometry better (Link-rods) AND the suspension TOP-NOTCH. They helped to create the AMA legal Works KYB kits (Well, nowadays you can run whatever million dollar set-up you want...so much for production rules...) and they have several different set-ups for variouse riding needs.
All I can say is that I love to let my friends ride my "Old-Tech KX" and continuously ask me,"Why does it handle so "Light'?" or "Yeah, but they don't handle like that stock...that must be some trick stuff..."
NOT!
The facts: You send it off to P/C and tell'em you want your stuff done...I recm'd you have'em set it up for off-road; BUT, firm enough for MX...they'll ask a few Q's and you answer them, tell them your riding ability (Be honest...) and a week later....the UPS guy drops off suspension and rods that make your bike feel and handle like it only weighs 150#s.
ACME does do nice work. I've riden a few well built KX500/YZ450 Desert rigs with his stuff and I've got nothin' but good to say about 'em; However, my bike seems to have more "SLAM-ABILITY" for some reason. On the other hand this may just be a more progressive damping/spring rate; because I've never had an ACME bike "Bottom-out" hard, either.
I'd have to say that I'd go with P/C for a modern firm bike and maybe with ACME for a straight-up desert rig that you want to be real plush.
Just my opinion,
Manny
P.S....you don't need any Hi-$ Triple clamps...just get some BRP Handlebar clamps and new grommets (I think the BRPs come with them) and you'll think you've bought a new front end! And, lube those steering-head bearings while you're at it, linkage too, for that matter...Hey, wait a tic...I've got my motor out...I need to put my grease where my moutn is!