It certainly is a dark art...I've been reading up on propgods and the E-tec forums for a while, props are a minefield not helped by the cost of the things.
I don't suffer any ventilation in the turns and it behaves the same as it did on the lowest hole just with an extra 150 rpm WOT, an extra knot or so and a cleaner wake. The hole shot has improved too. I came up a hole at a time and experimented lots last summer. Vipers like to run high from what I have read and it wouldn't surprise me to have to come back down a little if I changed props.
The vipers seem to work well on hulls that like a prop producing allot of bow lift but there are lots of folks out there who find they have a dislike of holding a slow plane due to this, especially if the boat is a bit stern heavy for its size.