I must say that I'm pretty smug with satisfaction already. They've only been in the tank for about three hours and I've already witnessed them cleaning the algae off of a few of the bits of gravel and working on some of the decor. ^_^
Plus, my betta seems just as chill about the otos as he is about the cories. He'll occasionally venture up to them, but once he's satisfied that they know he's the biggest baddest fish in the tank (ie they swim away), he lets them alone.