It's not the slave that causes the grab, it's the material of the clutch according to DDP (who installed mine and many others). They told me there are fibers that end up hanging off the friction material and that they cause the jerkiness. Slipping the clutch cleans them off (apparently).
So I can stop it for a while by letting out the clutch out a bit in first with my foot on the brake. After that it will be fine for a week maybe.
If it were the hydraulics then the slipping action wouldn't have any effect.
BUT, if someone can explain how my hyd's are causing this (and how slipping the clutch makes it better) I will happily run right out and buy new HD hyds!