The nice thing about distributed caches is that the closer the cache is to the user, the lesser the traffic traversing wide-area. So, the main hosting website wouldn't even see all that traffic!
But I guess these make sense only for static content...
"One of our user's site was under a denial of service (ddos) attack earlier this week"
I like the distributed website caching for static pages. Would be interesting to have pay for what was served model . . .