I was terrified to get rid of it. DS loved his, and was absolutely obsessed by it.
I was going to leave it out for the "dummy fairy" but I really wanted him to take the step...
We talked about it a fair bit, and I pointed out that nobody else had a dummy etc etc...
In the end (3 years 5 months) to be exact he gave it up. He just said to me one day that he didn't want it any more. So we threw it in the bin. The first few day and night sleeps were hard but I made a point of wearing him out as much as I could so he didn't have time to think about it.
It took him a couple of weeks, and he'd occasionally ask for it and I'd remind him. About a month after, he found a dummy in the car it was covered in dust and who knows what (vomit) and he dived for it and started munching away. I reminded him about how brave and clever he was now that he didn't need it anymore. He munched for about a minute then handed it back to me.
He's never touched one since (4 months ago). I'm so glad he made the final decision - I didn't want to do it as I felt heartless taking away his comforter.
Our experience anyway.