I agree that a lot of it has to do with how "at home" you feel in your own home. I had my first in a FSBC, and with this new baby, I went so far as to make an initial appt with a HB midwife before deciding to go with the FSBC again. A lot of it has to do with privacy and family issues. Our house has in-laws on both sides of it, and one or more of them is always home, so basically if DH was staying home from work anytime near my due date, they would all be watching like hawks and possibly barging into our house or trying to look in the windows to see if I was in labor. Zero respect for boundaries. My own family lives 20 minutes away, and they can be pretty darn intrusive as well, plus my mom would hold a grudge against me forever if my MIL knew I was having the baby before mom knew...
So yeah, for us, we definitely feel more privacy in the birth center. It helps that I had DD in the same BC, so we feel fairly comfortable there. Driving in labor is certainly less than ideal, especially since we're 45 minutes away. We definitely felt that subtle push to get us out the door that a pp mentioned (we left 6 hrs later, despite the fact that I had a hemorrhage). The birth center isn't perfect by any means, but in our situation, it beats feeling like we're in a fishbowl being watched by people on all sides.
If we weren't surrounded by in-laws though, I would definitely go for the homebirth.
