A lot of people are using their own modem, especially now that TWC is charging a rental fee.
Replacing a modem with a DOCSIS 3 modem could boost speed in the following scenarios:
•Being on a plan that needs a DOCSIS 3 modem, but only having a DOCSIS 2 modem
•Incorrect provisioning by the cable company
•Problem with the original modem (unlikely)
•Network congestion issues that are less prevalent when channel bonding is used