How much difference does say a 15" to a 15 1/2 diameter make? someone needs to start a prop demo service in havasu. I'd pay some bucks to rent a few sets before I spend thousands finding the right combo. Found a set of 15 1/2 30 pitch maximus's for a good price, been wanting to try these, even more so after a buddy said that a maximus took ALL the porpoise out of his 26. I dont think anybody has really tried these on OB's ?