You don't say what size the Header Images should be but you seem to use 1800 x 765 in the demos. Then you have set the header minimum height to 650. Then when the template is shown on a wider screen than 1800 the picture gets cut off a bit at the bottom but its not really nopticeable.

At http://www.whitchurchwaterway.uk I had some headers looking OK on smaller screens using images 1200 x 700 with the header minimum height set to 700; however now I am on a desktop with a bigger screen (1920 x 1080) I find some images are getting severely cut off at the bottom to the point of looking ridiculous.

For the pics I am using it would be good if one could control how they are cropped, i.e. top, center or bottom biased.

Either that or I must go back and reformat all my pics.

I think it would be good if the template somehow included some sort of guidance on selecting header images and what size to use etc.