I tried to get my son out of his crib at about 19-20 months. He always slept well, like yours, and we rarely had any problems getting him to bed. But man, when I "desecrated" his bed, his refuge, his secure place in the world, things fell apart. I really did get him excited about it, and he even kept asking me all day long to change his bed to a toddler bed (our crib has one side that comes off, then rails for the toddler bed). But that night, and every night that week, if he stirred and woke up even a tiny bit (which we all do, every night, but don't remember it), he'd get out of bed because he COULD. He'dd get out and scream by the door (he couldn't open doorknobs yet). I was a few months pregnant at the time and exhausted. So one morning at 3, all bleary-eyed, I converted that thing back to a crib. He slept the rest of the night perfectly, and every night thereafter. A few months later, I bought another crib at a yard sale and didn't even try to get him out in time for the baby.
Sometime after baby brother arrived, my then 2 year old started climbing out of his crib in the morning, and one day soon thereafter started eying the queen-sized guest bed that was in his room. He asked if he could sleep in it, and that was it! He never looked back.
I'd tell your son his options, ask him if he wants to do it, and try it out if he wants to.
That baby brother is 22 months old now, and I can't imagine taking the side of his crib. He would be into everything, never go to sleep, and would get up and destroy all within his reach before I ever knew he was awake. That's just his personality. With no new baby on the way, and two cribs anyway, I'm in no rush with this one. Also, I just don't think he would get the concept of our rule, which is that if you're in a big boy bed, when you wake up, you have to come get mommy and daddy up, too. My oldest didn't understand it completely at first, but he was much more likely to do it than my baby is. Without that rule, son #1 ended up smearing ketchup all over the kitchen one Saturday morning. He'd gotten his own "breakfast."
You know your son's personality, so you're the best judge of when he'll be ready. It's not like you can't go back (like I did), so give it a whirl if you want to!