Thanks for your replies. I'm not TOO worried about a little sugar, mostly because I don't think that eating it ONCE will do any irreprable damage, but I'd like to avoid getting in the habit of sweetening things.
I've heard (from colleagues at work) stories of one-year-old's gleefully shoving fistfuls of cake into their mouths, grinning with delight as they encounter that first sugar rush. I'd like to retain the sensuality of the experience, without the possible addiction -- but I love the idea of DS sticking his whole messy little hand into a gooey mess of a cake! So thanks also for the warning that I may be expecting too much in that regard.