We did. I'm rh negative and our third baby (rh positive, like all our others) was born unassisted. The midwife we had been working with dropped us when we decided to go unassisted for the birth, so we didn't have formal prenatal care from that point on.
I struggled with the issue a bit, but I talked to several people who had studied the issue in depth. As it was explained to me, in a gentle birth, where nothing unusual or traumatic happens (especially if the placenta stage is left alone - no rushing or pulling, etc), it is extremely unlikely the blood would mix. Even if the blood does mix, it isn't for sure that my body would start producing antibodies. And then, if I DID produce antibodies, it would have to produce enough for serious damage to occur to my next baby. So, statistically, the chance of serious complications for the next baby become slight.
With the rise of interference and traumatic hospital births, the problems from rh incompatibility became more common. Hence the development of Rhogam.
As in everything else in life and birth, there are risks either way and you have to decide which risks you will or won't take. The Rhogam shot has risks, too. For us, we had a simple birth, no red flags, the placenta fell out on its own within minutes and appeared to be a clean separation, so we decided it was unlikely enough we would have problems next pregnancy that we opted to skip the shot. I'm almost halfway through another pregnancy right now and it has been pretty easy with no indication of problems.
Personally, I would absolutely refuse any Rhogam shots before the baby is born because then it affects the baby (obviously, if you have any major trauma during pregnancy, that may be a reason to get it, but otherwise not). If you have been working with an OB at a hospital and you do an "oops", it would be easy enough to go see your doctor within the next couple days and get the shot if you want it.
Hope that helps!