If you are using fade in/out you may see an apparent jump of the image when the page first is loaded. It will depend on your image sized.
This is caused by the script that handles the fade in/out. This open source code was taken from the internet and the author acknowledges the issue but has decided to abandon the code.
With this in mind, feel free to use the fade in/out, but you will have to live with the issues
- if you have the blog title overlay, it will vanish
- the image is no longer clickable
- there might be a jump with the image.
You can always add a new widget area to the header and use a plugin like 'Dynamic Headers' inlace of the Atahualpa images in the header.