At first, I found that I had to go #1 before I could go #2 in a diaper. I've overcome that, but at the same time it seems to have un-conditioned the muscles a bit and I now can't hold it quite as long as I used to.
As for making you incontinent, I'm not so sure. I find that if I really have to do #1 or #2, and I feel the slightest urge to do the other, I can't just do one: it's either both at the same time or nothing at all. And this is with a regular bathroom, not diapers.