We kept our son in his crib until sometime after he was 3.
Of course, we travel a great deal, so he had slept in many beds (from about the time he got too big to sleep in a drawer...about 9 months...one of the most convenient places have an infant sleep, just don't shut the drawer! ;) to the time we finally moved him.
We kept him in his crib, primarily because it was the safest place for him to go on time out. And no, there were absolutely no resultant sleep problems, if anything his crib became his "safe place", where he could be as upset as he wanted until he calmed down. He also frequently slept with us in our bed, and like I said, had slept all night in real beds while we traveled since he was about 9 months old.
A note on toddler beds: They're a waste of money.
It's far far far more sensible to buy whatever size bed you'll be having him sleep in for the next 10 years or so. Put up a railing, or start off with just the mattress on the floor, and gradually build up.
We chose a double, so we can lay down with him for storytime/bedtime/reading-under-the-covers-pretending-to-camp-time/etc., and so he'll still be able to use it as he grows. <laughing> Of course, I slept in a twin until I moved out...but we also had 3 twins in one room. Our son's going to be an only, so space isn't really a big deal.
Good luck