You can select messages and press C-o to open the "Move" dialog, which has a select-as-you-type interface. (For example, I might press T, R to select a Trash fo

You can select messages and press C-o to open the "Move" dialog, which has a select-as-you-type interface. (For example, I might press T, R to select a Trash folder, then press down-arrow to jump to the Trash folder in my second account.) It's very, very few keys. However, if you're always moving to the same folder, I think you could define an Action with a keyboard shortcut.