RE: Hold-over or gradiated reticles?
I'm a firm believer in the graduated scope. I wasn't until a few years ago when I purchased my first Burris scope with the ballistic-plex. When set up properly and verified at the extended ranges it is terrific. I've since purchase 3 more I like them that much. They work. The only rifles I don't have these on are the ones that I know I won't use where shooting 300+ may present itself.
As for putting one on a ML - that's not my cup o tea but if the ads are right, that Nikon one should work nice for you.