Short version: we ended up keeping the Graco Nautilus.
One complaint I have about this carseat, this model, anyways, is that it has the cover and a separate piece of fabric that serves as padding. It has holes to put the shoulder straps through, but only for shorter kids. So I took it off. Well, that is when Ari began saying it wasn't comfortable. I put it back on the car seat, but it is annoying because it is not attached to the seat in any way. It's not a big deal or anything. It's just an inconvenience when you are in a rush and you have to take an extra second to make sure the padding isn't bunched up.
One pro about the padding: if the child has an accident, you remove and wash only the pad. No need to remove the seat cover, which would be a pain because you would need to uninstall and reinstall the seat.
Other than my one complaint, I am happy with the seat. Now she is comfortable. The seat has excellent safety ratings. It has the infamous cup holder. It cost us only $150. And it was easy to install it. So the Graco Nautilus will be our child's seat until she is done with carseats, me thinks!