I've decided, after battling the ENTIRE pregnancy with my husband over a homebirth, that its the mother's decision, one way or another. It is your birth. Everyone is cool with you having a hospital birth...and probably with having another cesarean section, even...because they aren't facing the emotional and physical consequences of it, of wondering if it was the right thing for your baby or for you, even. The thing is that birth is something you'll remember, reflect upon, and judge (or maybe even regret) for the rest of your life.
So, there are some things to consider. You are at a slightly higher risk for uterine rupture (though you now have the benefit of a "proven pelvis" on your hands). HB midwives will look at your vaginal delivery for any complications. They will prepare you and your body for the birth BEFORE labor to give you the best opportunity for safe birth (like rinking pregnancy tea, avoiding most OTC medications, etc). She'll also likely work with you on baby's positioning with certain exercises and stretches. I'm sure you already know that the less work the uterus has to do, the better it will be on the scar. So an upright position for contractions and birth will probably be safer than the on-your-back stuff you deal with in the hospital. You should also consider your transport time, in the event you need a transport. How far is the nearest hospital?
But, those are really concerns that you need to be comfortable with having addressed. I'm not saying that the opinions of others aren't important, because they are, especially when its family or the father. I think you should concentrate on the decision you've made, though, and then work toward getting them on board. I started this pregnancy with a husband who thought the CNM who would have delivered me in the hospital would have dreds and give me marijuana for pain relief, or something. So, he wasn't even on board with not having an obstetrician! I opted, at the very end, to do a homebirth with a different CNM, against his will. I sort of dove in head first, with hopes that he would come around. I often said to myself and others that, "He'll either be on this ship when it sails or he'll be swimming behind it to catch up." He was negative about the whole thing to the VERY end, refusing to pay for things like hose attachments (to fill up the birthing tub), birthing ball, gowns, vinyl table cloths, etc. During the birth? He was kind of distant, but really got to know the midwife and doula while I was in labor. By the end, he was smiling from ear to ear and bragging about the experience. Neither of us have any regrets. In fact, I'm pretty freaking proud that I stood my ground, for once, and made my own decision.
But, I do have to note, that you have one extra concern on your hands that I did not: the section scar. I'd had three prior successful vaginal deliveries with a proven pelvis up to 9lbs of baby. There was very little question about me, though she did stay on top of the strength of my contractions since I'd been augmented with all of the other births for "poor strength." They were just fine, btw. Hell. I went from 5cm to birth in an hour and a half with a 9lb 10oz baby.
Also...I had a variety of people tell me its "your decison, your choice, your birth." I always felt like that was callous and I tried to cater to the opinions of others. Honestly, though, its futile sometimes. That callous statement I got from others really was on-target. They'll be on the ship or left at the docks.