Sorry for the delayed response. But to answer your question, yes. I have over filled them and they do blow out alot of oil. But even when I have them below the low line, if I am running them hard, and especially when spraying, they blow oil like crazy. Now when I am spraying and running them hard, its usually through the whoops, so its hard to say for sure.

 

The breather barb on the stator cover is too low by design - the motor was not originally designed for its use on the DS so that's prolly why.
over filling the oil tank should not effect anything, the is a return oil pump in the crankcase and the amount of oil in the crankcase is not effected by the amount in the tank.
stock motors always blow a little, some more than others probably due to variences in piston ring gap.
Perfectly gapped piston rings on new rebuilds blow next to nothing, gapless rings on the new CP pistons blow zero.

it is fine to run the breather tube to the intake boot barb, but any oil that blows out in an off camber sidehill situation or unexpected rollover will be coughed into the intake boot and may may a little mess - not a problem other than cleanup from what drips into you airbox or on your swingarm.