I left about 1 ounce out of each tube when I rebuilt my forks using Progressive springs. The ride is just fine. Like what was previously mentioned, easier to add than to remove.
What did Progressive springs do for the ride? What difference did you notice?
Front end does not feel as mushy. I had seals leaking that the sealmate trick no longer helped. I figured that since I was taking the forks a part to rebuild them anyway, why not the springs too? My 2 cents on front seals: if you have to start using something to wipe the seal and tube surface to clean out road crud it's time to start thinking about rebuilding. There was a noticeable difference with new seals when reassembling the tubes.