Wow, this is a terrible idea. Pointing all your domains to a service you don't control with no formal, legal contract on what they can and can't do with the domains you point at them?
I'm a little late to the discussion, but I have to point out it's actually very easy (and free) to create your own "Wwwizer" on Heroku (this assuming that your DNS service cannot solve it).
It's just 8 lines of code.<p>Shameless plug, but if you want instructions: <a href="http://bionicspirit.com/blog/2012/01/10/domains-merged.html" rel="nofollow">http://bionicspirit.com/blog/2012/01/10/domains-merged.html</a>