I think that when you create an extmfd object, it automatically opens in windowed mode.
I have the Orbiter graphical elements, and main application open in Full Screen on one monitor. ExtMfds open in their own "mini-windows" in my other monitor.
I have a pretty good system (Core 2 Duo 3.0hz, and 9800GX2 graphics), and I have each monitor being rendered independently by separate video cards. So I don't think that the hardware is being taxed too much.
It just seems to me that vsync loses it's effectiveness when these "mini-mfd windows" are open.
The tearing is only evident when panning the camera or rotating the camera quickly. If I close all of the extmfd windows, the tearing goes away.
I guess I'm not so concerned about the problem, this isn't a First Person Shooter.
It's just, if there is a solution, I'd like to make use of it.