I have very limited experience with both of the knives in question, having handled both in the local knife store. Although I wasn't overly impressed with the particular specimen of the Pinnacle (the blade was far duller than I expect from Benchmade, and the lock barely engaged the tang), I think it felt better in my hand than the S-2. The S-2 handle seemed too dramatically curved (like a banana), and the clip has an uncomfortable, outwardly protruding point at the end. I think I could get used to the curved handle, and may actually grow to like it (I like bananas too.) The pointy clip could be easily improved with a Dremel.
The recurved blade of the Pinnacle might offer some advantages in cutting, but could be a bit tricky to sharpen.
Assuming I could find a satisfactory specimen of the Pinnacle, I'd probably favor it over the S-2, simply on the basis of good experience I've had with other Benchmade knives I've owned.
David Rock