Hi!
I haven't been there yet but in a few weeks I might be able to give you my own evaluation.
My mum had 2 children both natural births, one just under 4kg (me) the other just over 4kg (my brother). She likens labour to being really really constipated and then having to pass it. She says it is definitely painful, but not the worst pain she has ever had. She says mastitis was ten times worse than labour pain.

I do believe that your mindset plays a big role. When you are in labour and you can remind yourself that this pain has a reason and is your body doing its job to give you the most wonderful little treasure, then maybe you won't suffer from it as much. On the other hand, when you have a miscarriage, there's nothing positive about it and the emotional anguish will add to the physical pain.

But hey, so far it is only theory for me. I can't wait to experience it for myself.