Cory's still getting along great with my betta. He's quite the little troublemaker, swims up to the nest, pops a few bubbles, and then makes a run for it - betta gives chase, but always returns to his eggs. He doesn't seem to care about the eggs at all.
I'm still thinking about adding a few more panda corys, but I'm not sure if I have the space - maybe two, possibly three, but I'm not done stocking yet. I've also been considering some Thai micro crabs, people say they're okay with bettas since they stay small. The store where I got Cory has some more panda corys around the same size, so I might grab a couple more. It seems like Cory stresses the betta more than he's stressed himself, if anything.