what would be a good "fallish tart-sweet apple? Would a local, new harvest Macintosh apple be too mushy?

I think Macintosh would work great. The grated apples work almost like apple sauce as part of the batter, so it doesn't matter that Macs get a little mushy. Susan's suggestion of a combo of Mac and Granny Smiths is also a great idea! I'm going to try that next time.

I love the combination of Macintosh and Granny Smith. You get the tart of the GS and the sweet of the Macintosh. Yum!!