I agree that Track Motion is what you want when you need to move something completely off screen. Pan/zoom is really just for moving around inside a frame.
But even easier than that would be to just use a transition; there are dozens that are _designed_ to move objects off screen.
>ps – I have used other video editing tools (i.e. Media Studio) and I find the Vegas’ Pan/Zoom function complicated.
I came from MSP also and you’re only partially correct. The Pan/zoom is _different_, but much easier to use once you get the basic settings correct.