My son is three and although he goes to sleep in his own bed at some point during the night he does end up in our bed. He didn't start this until he was in a bed. I plan on letting him continue this until he is 4 or so. If he is happier with me and my husband and our bed is big enough I don't see an issue with it.
My son just turned 5 and always falls asleep in our bed then we move him to his bed before he goes to bed. He would fall asleep in his bed if i made him but it devastates him so i figure he will do it when he is ready. My dh leaves in Feb for 16 weeks im a little worried he will end up just sleeping in my bed. I mean its a.king size so there its plenty of room lol.