It's been my personal experience that buying a Download is putting your complete trust towards the seller to provide you with the content you expect, and to do it for the future if needed. This isn't always the case.
I reluctantly bought the Dirct2Drive download of the U-Boat Missions Add-on (I just couldn't get over the fact that UbiSoft wanted to be
paid for its fifth patch to a game I original paid $50.00 for....their last patch that
still doesn't fix many issues with the game!!). However, as the years went on, D2D required you to get a new "Access Key" to re download your original content ("so they could keep an eye out for pirating"), every time you reinstalled the game. This wasn't
too bad, you just needed to jump through their hoops when you wanted to re download. The real issue sprung up when D2D was sold and another Download company took over. You had to prove to the
new company that your original purchase was legitimate, before you could receive your content again!! That's when I started to look around for a DVD "Gold Edition" of the game. As I said, last year you could buy it for the same price as a download.
Forget it....... buy the disk and thumb your nose at 'em!!