I worry about DD 17m trying to walk around her cot in her sleep sack and falling against the bars and losing a tooth! But she throws her blankets off and wakes up cold (she's probably not really old enough for blankets according to official advice anyway). I've seen sleep sacks with legs, but only online, so can't see how thick/good quality they are.
Are you still using sleep sacks for your toddlers? Am I worrying about nothing?