I loved our crib tent. I started using one when my son was 20 months old and used it until he turned 3 and we transitioned him from the crib to a twin bed. We purchased the crib tent because he threw himself over the rail 3 times in one night. (The mattress was at the lowest setting and the rails were up.) It's been worth every single penny we spent, as I'm sure it saved him from an injury. There no way any child could tear down or get out of today's crib tents -- they wrap around the outside of the crib and under the mattress. No safety issues at all.
I knew that if I tried to transition him to a bed at such a young age, there was no way he would stay in it. My son needs his healthy sleep -- not the nightly bedtime battles so many Moms experience. Around the time he was 2 1/2, I found myself forgetting to zip the tent occasionally...and he never climbed out of the crib! It's as if this tent helped him transition back into the crib, and he loved being in his crib again.
PS...My son's transition to the big boy bed was really quite easy -- very little of the getting up and leaving the room, back-and-forth. Keep your son happy in his crib as long as possible and you'll have much less trouble with the bed transition. Good luck!