Thanks for the suggestion.
I understand that SB5100 is not a D3 modem and will not be able to handle the channel bonding. But I don't intend to have the service faster than 20 Mbps which can be handled by single channel.
A post on DSLReports forum (»Only getting max upload speed of 3 Mbps on 30/5 with SB5100
) indicates that TWC actually was still sending its customers the SB5100 modems last year, which makes me believe that it may be still compatible with TWC's headend equipment..