My oldest son was @ 12 months and we moved him b/c he kept climbing out of his crib! Auntie bought him a firetruck bed and the transition was a breeze!
2nd son was closer to 2y/o when he started escaping and his transition was just as easy b/c by then we had bought the boys a set of bunk beds and they were both in love with them and the idea of sharing a room, which they had to do to make way for baby sister!
Daughter was exactly 2y/o and we moved her not b/c she learned to climb out of her crib but b/c MIL bought her a cute twin size bed, she was also easy to transition b/c she loved shopping for her new sheet/quilt set, she's such a girl!
~I agree that at 2.5 he is too big for a toddler bed, it will be a waste of money...if I were you, I would go straight to a regular size bed, twin or full, whichever way you are going to go.