I just noticed one fatal flaw in these templates. If you have any description in your profile the template completely falls apart because it changes the height of the profile bg area. The longer the description text the bigger the problem:
For these templates to work your bg image has to have the width and height in same proportion as the width and height of the bg area in your profile. Needless to say this makes a standardized system practically impossible. But if you still want to know exactly what your profile background will look like then keep the width the same as in the templates and match the height to the height your profile bg area after adding all the description texts and web adresses. And since the profile bg template is double sized you will have to make the height twice the size as well.
The image area seems to grow downwards as you add more text, so if you match the height you only need to add new stuff in the lower part of the image. The area above the transparent grey box will stay the same.
This was supposed to be simple but it ended up extremely complex.