It is for Heston Blumenthal's bacon and egg ice cream.
I'm not super familiar with this particular recipe but would probably suggest 2:1 brown sugar to maple syrup. I think your idea is spot on but would cut the maple for two reasons.
1) I would think that the maple syrup would thin/liquify when heated and possibly "slide" off a bit.
2) I think maple is a very identifiable flavor. Sounds like it would actually work well in the recipe but I'm guessing that cutting back will give a more true-to-recipe flavor.
But, it's ice cream, so you really can't go wrong either way!