The procedure is pretty simple, really - I remove one set of bearings from each rocker (so that instead of quad bearings it's just double) and machine the rocker from 12.7mm to 10mm thickness.
|After (note the ceramic coating, too)|
The total weight savings is about 100 grams, which isn't a ton, but this mod is free if you're buying a full suspension frame so the price is right ($0/gram!) If you already have an FS bike from me and want this done it'll run you $50 (including return shipping to wherever you are in the US). If you have a Ventana (or any bike with a Ventana rear end that I didn't build) and want me to do it, it's $75.
Downsides are basically that you aren't running quad bearings anymore (so potentially shorter bearing life, though I've never had any problems) and a look that some people may not like (ie bare machined aluminum next to black anodization). Quad bearings remain at the main pivot and those are the important ones for stiffness so you don't give up anything, really, in terms of performance. Of course, if you find that you disagree, you'll have to order another set of rockers (about $150). No, this does not void your warranty (ie, I'll replace your rockers if you break them) if you're riding one of my frames.
Anyway, easy way to save a few grams if gram saving is your thing. And a nice boring blog post for a slow, snowy Saturday afternoon.