I wouldn’t cross it off your list. Mine (4th leaf) had a couple hundred apples this year and were still yellow as of Thanksgiving week. More importantly for a northern guy they have a really late, long bloom time. There will be years this may be the only apple on my place. I plan on grafting a few more. Probably will be top works, I don’t think you would want a large % of your trees to be GH but a couple and a few branches on other trees would be a great addition. It is also hardy for zone 3 which is not listed anywhere but mine has been through 3 winters and seen temps in the -30’s