Mercury quote the prop as being recommended for v6 outboards so should be right for opti 175.
I bought it for better acceleration as I wakeboard and also better low speed handling as it's a slow ride to where I wakeboard. It is also supposed to give better cruising and big seas performance but I haven't really used it for that.
My pick up was a lot better but I am comparing it to a 3 blade Ali prop with a different pitch so lots of variables in there.
As mentioned you do lose top end with 4 blades (although mine actually increased, but like I say other variables at play here).
Mercury do a good write up on their props (and there are short videos on you tube as well), I know they are sales messages but whatever you do, its worth taking a look to see before you buy one.