Hi Summerfruit,
I'm in a very similar situation to you. Ds wasn't as big as your dd (8lb 4) but was 10 days over, long labour, and ended up being delivered with ventouse.
Our second one is due April (8weeks today omg!)
My mw suggested a hb to me at my booking appt. I was wary at first, considering my first birth. But as time has gone on, each mw has fully supported our decision for a hb. They have told me that if you stay at home, you are more relaxed, you feel more in control, and therefore there is less chance of any medical intervention iyswim, regardless of baby size. One mw I saw said that as long as you're not high risk, then there's no reason why you shouldn't have a hb.
(btw, I've heard that its easier to give birth to a bigger baby - not sure how true it is )
We have a pre-birth appt at 34wks where the mw comes out to our home, and we go through every option with a fine toothcomb. Do you have this?