I can not make a suggestion without more info, but this may help you!
If Raw Water cooled and if in Salt water, your final temp should be in the range of 145*f to avoid salt crystallization of the enigne/manifold internals. Higher temps and crystallization add to the rust scale within the block and heads.
(There should be some good information on this on the Internet or in your OEM manual for raw water cooled engines.)
If Raw Water cooled, and if in Lake/River water only, there is no reason to run the colder stat, IMO.
If you have the Closed Cooling system (aka FWC :rolleyes
then you can also run the warmer stat. 170*f/180*f final temperature should be ideal!
So my question for salvy would be; which cooling system do you have..... and what type of water are you boating in?
Just my two cents from what I've learned myself!