The new 20 rudders are definitely less likely to stall - the old pin-style rudders were very prone to stalling. I wouldn't change your rudders or the rake in the mast for whatever wind strength you were sailing in - there's nothing wrong with them and I wouldn't say there's anything wrong with the lee helm you are experiencing. You did win, afterall.

I would rake your rudders more forward to try and balance them a little more if the lee helm is uncomfortable. Certainly too much lee helm can make sailing fast difficult just from the pull on the tiller. You may have to grind a little on the rudder itself to get enough clearance for additional rake.