105 Octane worth it?

I have twin 300 OBs on my boat. Merc says I need 91 and I always run 91. So is there any benefit to running 105 or a 50/50 mix of 105 and 91?
In cars they say it's a waste to run any octane higher than what's recommended, does the same hold true for boats running in 110+ temps?

My thinking on this has always been that you -may- notice some seat of the pants improvement, but unless you're willing to change your tune (basically timing and fuel, and not sure how you do that on O/B's) you won't really be able to take advantage of the 105, and probably not worth the extra cost.

for the money..stick with the super. The condor has run on race gas and it runs better until the lighter fractions boil off..and it smells a little different..like 100 dollar bills!
CC

Thanks guys, kind of figured as much. But the 105 sure does smell good :D .

If you really like that smell, CAM 2 makes an additive/octane booster to give you that cool exhaust funk...