How much can one reduce the sugar in this cake -- 1 cup, 3 ripe peaches notwithstanding -- without affecting the structure of it? Thank you. ;o)

So, to report . . . I tossed the plums, which were a bit tart, though ripe, with about 1 tablespoon of sugar, instead of 2, and used 1/2 cup of sugar instead of 1 cup in the batter. It turned out great! I crushed a few cardamom seeds with the grated nutmeg, and sprinkled a couple tablespoons of chopped roasted pecans on top, with the raw sugar, for a bit of crunch and flavor. So pleased with the result. I'm looking forward to making this with peaches next time.
Thanks for your help, everyone. ;o)

I remember reading that, in general, you can cut the sugar content of baked goods by 1/3 and still maintain the structure. I usually go by that when modifying a recipe.

Having not made the cake, I can only surmise....but I figure since it seems like the hand-creaming process doesn't give the cake THAT much structure (and its only 6 T. butter), you could probably cut it down to ¾ c. without affecting it too much.