I skipped the maple syrup as well. Amazing! My husband and I loved them. I will be making this again!
Make sure to use really ripe nectarines and skip the maple syrup, then it is delicious. The syrup ruins it and a grilled ripe nectarine doesn't need any more sugar. If you have to add something, use honey not maple syrup. Served it at a BBQ last night and guests loved it with Rose wine! it was the first appetizer to get eaten.