The Dry/R is really a step down from the normal PG, which is IMHO pretty strong. The Dry/R fits IMHO well "under" a normal PG (had one, know both balls, but sold mine after a few games because it was a production turd that flared backwards...).
The Dry/R's coverstock is very weak/smooth, you should see less overall motion and a softer breakpoint with it than with a PG drilled the same. How it compares to a Neptune I cannot really say, I have only seen 2 Neptunes in action up to date and not used one myself. But again, I'd guess that the Dry/R fits under it, too, because of its high RG that pushes the ball well down the lane. I woudl not call the Neptune "rolly", but due to its true core it gets into a roll sooner, so I'd consider it a medium-dry ball, like the PG, and the Dry/R as an option if the line fades away.
--------------------
DizzyFugu - Reporting from Germany
Confused by bowling?
Check out BR.com's vault of wisdom: the unofficial FAQ section
Secrets revealed: What's a fugu?