What do they say about teaching grandmothers to suck eggs? I was impressed because I know first-hand how difficult it can be to get a good key sometimes.

IMHO, the key (pardon the pun) to getting a good key is not to subsample your chroma. You can do what you like with lighting and software tweaks but if you've started throwing colour information away before it's even left the camera, you've already lost the battle.