Please do not abuse these sort of services. Sure, downloading one-offs for legitimate personal use is fine (in my opinion) but please be reasonable and avoid discouraging them of publishing more stuff or even locking down the existing collections more down.
Sure I understand it's bit annoying that they do not provide the higher resolution as downloads, and that they don't have more liberal license. But it is still pretty nice service and reasonably well done imo. This could be the baby steps for more open collections, but egregious abuse probably will not help in getting them into right direction.
What kind of dimensions do you get from the tiled downloads? I grabbed a few of the 'large' JPGs the site offers and wonder how much of a difference there is.