Honestly hun - it doesn't matter if they're 5lbs or 10lbs - when they come out they all hurt.

I'm not trying to be cute, there is no difference in terms of pain birthing a larger baby than a smaller one.

As far as the ultrasound estimation of weight...pfft it's more likely to be wrong than right.

And even if it IS right - you have previously birthed a baby only one pound less than that. Your body can do this, give it that chance. A caesarean is no picnic, no matter what they tell you about how "good" and "easy" they are these days. They hurt. You can't roll over in bed or get up without help for a good week. You can't pick up your older children for much longer. You will have a scar on your belly for the rest of your days. Caesarean surgery IS major. Wonderful things for women who need them...but on the face of it you don't. Don't put yourself through all that on a "maybe".