I'm far from an expert on this as I just put installed a Pro 700 in my 4430.  What is your p-gain set at?  Have you done the dead zone calibrations?  I have my p-gain at 6.5 and my aggressiveness ALL the way up.  Swath acquisition is also maxed out.  I'm about to drive 12-14 mph down 30" rows.  If I increase the p-gain too much my machine will get unstable and start whipping around.