Compression check will verify top end health.... Some are good for 700-900 hours, dependent on care.

X2 on the impeller- do it. My gimbal blew last year at 170 hours. Did full bellows and water line replacement also .... Lotsa fun!

I will check out the compression this spring. I got a warranty with the boat and the dealer seemed really good to deal with. I will definitely changed the water pump. I did that on my old boat regularly as well. It was an omc drive and was super easy to change. Not sure where it is on the merc. I had a survey done and apparently the bellows and gimble bearing were checked as much as possible.