Here is the way I have my RG arsenal set up and it works great:
Cell- Heavy
Cell Pearl #1- Medium Heavy
Cell Pearl #2 (drilled weaker) Medium
Grand Illusion- Medium
Venus- Light
Golden Globe- spares
I would pick the Venus over the Neptune, much better ball for lighter conditions IMO. Also, I would drill your Grand Illusion strong. Keep in mind the Cell Pearl is a very strong pearl ball that can handle some oil.
Good luck with your arsenal..
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My first child.. Hannah Allison Kiser born 4/30/2007... My little angel..
Roto Grip.. King of Them All!!