He's basically telling you it really won't matter if you go with either the DOCSIS 2.0 modem or the DOCSIS 3.0 modem. :)
Since you can get the DOCSIS 3.0 modem for less than the DOCSIS 2.0 modem, I would get the DOCSIS 3.0 modem. A DOCSIS 3.0 modem is backward compatible with DOCSIS 2.0...