I also wonder, then, if they are being anti-competitive. They essentially limit large backup (~200GB) to use their service or risk going over the usage cap. What if I sign up with Moxy directly; will that apply to the usage cap? How about a competitive service such as Carbonite or the new favorite Dropbox?

I see legal issues galore over the way this service is offered. For instance, I am not interested in file sharing much; for that I use either Google Documents or for larger things, my 2GB DropBox account (which maybe I will expand as I fill it). If my drive crashes, and I use a non-Comcast backup service, it is not even possible to do a restore unless I do it over several months [and that may not be possible with some providers which maintain a backup for 30 days] or go over the 250GB limit and get my threat email from Comcast. These are all issues I intend to get answered from Comcast before long, if I can ever get a knowledgeable person online.