[Brian]

Chris - the Apple text system uses "Option plus <some key>" to let you type other characters that don't appear on the keyboard keys. For example, holding down the Option key and hitting "1" will get you a "¡" character. That's why those shortcuts aren't working - the text system is using them for something else.

With the command keys, you'll see it work if the app you're typing that character in isn't using the keyboard shortcut for it's own purposes. In the cases where OmniFocus doesn't appear, it's because the application uses that keyboard shortcut already.

In case it helps, I use "Command-F6" for my clipping shortcut. It's easy to type, and other apps don't tend to have it assigned to something else...