I don't think Comcast will ever offer 305Mbps service using DOCSIS 3.0. If they ever do offer such speeds over their HFC network, it would probably be by using equipment built to the new, currently-under-development DOCSIS 3.1 specs (see: »Re: Dream Modem - 24x8
Also see Jeff Baumgartner's blog item today about all this:Will Broadcom Go for More Than 1-Gig?
By Jeff Baumgartner, Light Reading Cable - January 8, 2013
»www.lightreading.com/blog/docsis ··· 40145759