The bandwidth of downloads via DCUpdate may not add up to much and im not sure how you are sitting on the bandwidth front. Would it be feasible to add swarming capability to DCUpdate and some of us can enable "seeding" mode so we can help out in serving your updates? I think the bittorrent protocol is pretty well documented. I know I would be willing to seed updates. In this case, the program would automatically download and save the updates and immediately seed even if I haven't installed it. Possibly add the option to automatically silent install updates and run the new version.
I am just babbling here.