When I build Schumacher shocks with 100% rebound, the cars seems very darty and unsettled. I've played with less rebound, but haven't done enough focused testing to be really confident of the results. The car does seem more settled, but it seems like they may pull air in and go flat after just a race or two.
On the advice of one of the local fast guys who swears by holes in the cap, I got myself a pin vise and some small drill bits, and got to work. It took some patience with the aluminum caps. The holes are something like 1.5-2mm, which is probably bigger than ideal, but I messed up the first one and felt like I should do them all the same.
With this set of shocks, I build them with "100%" rebound... i.e. I pull and hold the shaft all the way out, gently press the bladder in, and then put the cap on. Like this, the shocks are basically "dead". The shaft just stays where I left it. If I push it all the way in, it'll rebound a few mm very slowly. The car handles smooth and consistent, and they seem to stay that way for quite a while without needing a re-bleed.
-Mike