M7 (Merton 7) is actually an ancient French apple bred in 1688 called "reinette doucin", or "doucin vert". Contrary to what some us websites claim, M7 is not a descendant of this apple, it actually IS the doucin vert, at least the virus free version from the malling research station's de-virusing efforts (heat treatment.)

Doucin vert has been used as a rootstock for centuries, it's not exactly grown for its fruit. It's definitely NOT a McIntosh-like apple, that's really wishful thinking. See the picture below from the GRIN DB:

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I recognize this apple from abandoned trees in some orchards around here. It's really just livestock fodder, not even cider grade because it's not very juicy. But then again, it was an abandoned tree, neglected and not watered, so the apples from the rootstock suckers were small and dry.

Now MM-111 is a bit closer to your description. It's a red McIntosh looking like apple, except that it's ribbed. And it's a pretty big apple too, looks juicy and tasty in the picture, but I've never tried it, it's most likely very close in taste to Northern Spy. MM-111 is derived from multiple crosses. The first one is Northern Spy X English Paradise, which was then crossed once more with Northern Spy.

See the image below:

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So M7, forget it, graft them over to something decent unless you just want to feed your pigs, but MM-111, there you might have a better chance at a good cider and cooking apple.