If you have a part cooling fan or use ABS with no fan, there's no cooling issue. I usually print that hinges one at a time.
About the teardrop holes, they're made at purpose to avoid bridge trickleing on top of the holes, it's a nice 3D printing trick. No problem about that. The holes still constrain 75% of the screws which are perfectly hold in place.
Actually that hinge is the most downloaded and built of my designs. No issue were reported yet. I printed about 20+ hinges on different printers with same success. The Mendel90 is a pretty good printer, I'm confident everything gonna be all right.
I wish it will suit your needs. Regards.