Dr. Drang, bouncing off my recent post on Reminders:
If you have the Move tool in your Mail toolbar, you can select all the messages you want to move, click on the Move tool, and select the appropriate folder from the drop-down menu. Because the menu is long, this may seem no easier than dragging and dropping, but it is. The key is that once the drop-down menu is active, you can start typing the name of the folder and it will be selected. Boom.