I would give my kids a moderate amount of artificially sweetened food as an occasional thing. It is obviously a huge grey area. Real maple syrup doesn't last long in our house, and when it runs out my kids just use my sugar-free maple-flavoured syrup, which they like. I try to tell them not to, but they figure if it's good enough for Daddy....

When I make pancakes, for example, I make two batches - one batch with flour for the rest of the family and one batch with psyllium husks for myself. The only low-carb cake I make on a regular basis is cheesecake, which my kids don't like anyway. But if they did, I'd probably make two cheesecakes at a time (one with sugar and one with artificial sweetener).

If you were to use say Natvia, that should be ok.