RE: kevlar vs peel ply hinges
I prefer kevlar. You want to cut the strips on bias. 1.7 ounce (.003") can work but they can break on impact. 5 ounce is a little beefy and makes a bump on bagged foam core wings. 5 ounce works great on molded wings.
Since peel-ply doesn't bond well with resin it's prone to delaminating. There are quite a few manufacturers who have used it though. It's just not my preference.