It's a good idea but I am one of those people who don't like large changes in animated files.
In the banner the whole image is changing and it can become distracting for some people.
A better idea in my opinion would be a simple PHP image rotator. You could use each one of them slides as extra banners and randomly change it to a different one on each page load.
ArmedAssault.eu does it, and it works quite well.