Are you saying that an appendix has the same value as a 8 week old fetus. Why then would an assault leading to a burst appendix get somebody a year or two in jail (at most) whereas the same exact assault leading to the miscarriage of an 8 week old fetus could lead to more than a decade in jail in many states?
The Spartans drew the line on abortion some time shortly after birth, I don't imagine you would advocate practice that even if it was conclusively proven that infants are not sentient. What about 1 day before birth? Seems kinda arbitrary doesn't it? If the baby is viable would it not be more humane to just extract it and give it up for adoption, it wouldn't be that much more dangerous medically. Let's go the other way now; should we draw the line on abortion at the moment of conception? That's a tough sell, especially since it would make murderers out of ever woman using an IUD.
What I'm trying to say is that nobody will get anywhere in this debate if we use the slippery slope argument and hyperbole to attack the other side. As a wise man once said, the slippery slope argument works both ways.