My 5.5 yo is in pullups/dipes at night. He also was my easiest to day train with the potty. He was also dry most nights until we had a big upheaval in our living circumstances.
He's mildly embarassed about the dipes, but prefers them to waking up in a wet bed in the morning and I prefer that to the frustrating of having to strip a soaked bed every morning, hoping I had enough padding in there to save the mattress.
One thing that has helped is setting his alarm for 5.30 am, so that he can get up, pee, and then go back to bed. That seems hellishly early, but he actually likes it because it gives him a sense of control--he gets to jump up and turn the alarm off and he gets the benefit of dryness when he wakes up a few hours later for the day. He's always been very independant and "I'll do it myself" so it's only rarely that I even need to get up and help him wake up.
He's been dry most mornings, but we're sticking with the dipes for a while.
My son is 2....but he has horrible night terrors if he wakes up and has to pee, so we take him every night around 11 PM to pee. He pretty much doesn't even wake up at the potty - I hold him up and tell him to pee, and he does. Then I just carry him back to bed. The upside to that is that he stays dry at night. We still use a pull-up just in case because every time I put undies on him at night, he pees. But when I put a pull-up on him, he stays dry. Weird, huh? Boys are curious creatures, I have decided that. :)
Our son was in nighttime diapers (well, Goodnights) until he was 7 1/2. His body just wasn't ready until then. When he was 7 1/2, I began to get the sense that it was convenience rather than night time incontinence, and I asked him to try it without. He'd also begun waking in the middle of the night when before he'd sleep soundly all night. He asked what would happen if he peed during the night "you'll get wet, the sheets will get wet and we'll have to change things". "Ok," was his response. He tried it, stayed dry and that was the end of it. There's a family history of bedwetting, so I wasn't too worried.