Hi Sarah,
Tyler was between 17-18 months when we switched. He started jumping out of his crib even though we had it on the lowest setting. We would come in to get him in the morning or after nap and he would be wandering around his room?!?!?!?!
Luckily we were not having any real problems with his sleep prior to the switch, however it seemed like his naps and overnight sleep got longer once we switched. Actually, he might not be sleeping as long but is happy to stay in his room for a long time since he can get to his books, stuffed animals, toys etc. Even if he wakes at 6:30AM we do not go get him until 7:30AM. He will happily play in his room till then. Same with naps. This is from an extremely spirited active child.
It only took one or two nights and one or two naps after the switch where we had to take him back to his bed.
HTH!
Judy