I got a little confused with the surf/skim comment. The oogle is full on skim, if a bit large. So I'm interpretting the "surf/skim" comment as a less skim and more surf style board.
There are hybrids out there like the Walzer and TWP Composite X 4.5 with 2 3/8" turbo side bites that might be more to your liking if I misunderstood your question. I have heard rumors of a Phase 5 twin fin also, but haven't seen it.
The F-18 is the Bullet without the wings or the single concave. The Bullet is the more responsive of the two. If you've mastered all those other boards, the F18 won't feel much different. The Bullet will have more rail to rail responsiveness and if you can do aerials, that board releases better than the F18.
The Bullet over the F18, IMO