Slightly overcooking and blending the chickpeas when warm (NOT HOT!) will help the dip blend and overall, create a smoother dip.
I've used brown sugar in this dip and loved it. You'll have to add more than ¼ cup and adjust to taste since brown sugar isn't as sweet as maple syrup. I didn't have trouble blending it, but if you do, you can add 1 tablespoon of milk at a time - but not too much since you don't want the dip too liquid-y!