I use 20/50 exclusively in my primary... it's always worked without issue, so I see no need to change.
ATF might be cool for finding the origin of a leak... but who's bike leaks?
So moot point there.
I also pre-oil my drive (cork) plates before assembly, as they run in a small amount of oil anyway, I can't see what it would possibly hurt. Plus it seems that this would offer some protection against glazing upon initial startup.
I second the notion of good plates as well. I use Surflex in my (dry primary) belt drives, but Barnett's have always done well for me in oil. Also MAP Cycle (
www.mapcycle.com) makes very nice clutches made to run Wet or Dry, but I'm not sure if they have P.U. setups.
Ryan