Make a backup of your Moneydance data set.
Upgrade Moneydance to 2017 and check all but printing works.
Make a FILE - BACKUP and put a copy of this backup on say a memory stick.
Then upgrade to High Sierra to get printing working.
Sounds like a good plan. When you say in your first line to make a backup of the MD data set, do you mean another backup separate from the ones that I now have automatically made and sent to my documents folder when I close MD each time?