I think the due date thing with my midwife bothers me more because she didn't listen to me. Not so much the specific date.
Besides, I've never gone near the 42wk point (when everyone starts to panic), so I don't see the reasoning to give me extra time. Especially when my 2nd was 38 weeks - that difference of a few days on my chart would cause them to push a transfer, thinking he was "too early".
For potty training/learning/EC'ing, we EC'd our oldest until he was around 8-9 months, he got roseola, weaned and went on a strike. It was a lot to take in in one week. But he was fully trained (aside from overnight, but that's a different issue) before 24 months.
I didn't EC the second because it was too much to stay on top of, and he too was out of diapers before 24 months.
And now with our third (a girl), she started voluntarily going to the toilet around 15 months, it was just such a novel concept to her :) But until it's a little warmer out (and inside our house!) I've been keeping her in diapers, it's not that she's not ready to advance, it's that I haven't put the time aside to follow up. I know I know, bad parenting. She's capable of going by herself, pulling her tights down and up and making a decent attempt at wiping so I have no doubt she'll catch on within a couple days once I make a point of helping her along :)