Has anyone tried using a sleep sack with an older baby ?

My son is almost 14 months old and he still sleeps in his sleep sack. He can stand up and move around his crib pretty well in it. If he falls it's OK since I have the crib pads in. My son rolls from back to front a lot when he sleeps, so the sleep sack works well since I don't have to worry about the blanket falling off of him when he rolls.