My DS, who is 3.3, has been dry at nursery (3 days a week)for months and months. When he comes home though he will not countenance sitting on the potty or loo, and insists on nappies, to the point of hysteria. In fact, I think he's only ever done one wee in the potty at home.
While it doesn't both me majorly (easier to go out and about on our days off), I've noticed that while nursery say he drinks normally when he's there, the moment he gets into our car to come home (in a nappy) he downs a whole beaker of juice/water, and fills the nappy in about an hour. He also saves his poos for home too - cheers...
So, am I right to just wait, on the basis that he'll eventually want to lose the nappies completely? No amount of "you're a big boy now" or sticker charts seem to work - he's unfortunately as stubborn as his mother. Grrr, those pesky genes!