Wow, Tom! I'm totally amazed at how similar the two look. But I think you hit the nail on the head. The terete leaves of the Cerato. are much plumper. And there's actually a bit of difference in the flower's lip too. Still, I'm astounded at how similar they look.
Oooh...Very exciting. Got quite a little debate going on! Max. uncata vs. Cerato. clathrata. I'll be really interested to see more info and opinions crop up!