I called twice and talked to 2 reps. They both said TWC won't support the SB6121 modem. I think this is nonsense since it is exactly the same as the SB6141 but has only 4 downlink channels instead of 8, which means top download speeds of only 160 Mbps instead of 320 (Google SB6141 vs. SB6121 for reviews). Seriously? I am on their turbo plan and get 30Mbps MAX. I have no need for anything faster, but even if I wanted 5 times what I have now the SB6121 would be fine. If anything I would buy faster upload than what I have now. Anyway, TWC is a racket. They sent me a postcard saying they were going to start renting their modem to me 2 days before the new billing period. Scalpers. (I'm in the Rochester, NY market.)
I just had it activated on Time Warner Cable in Northeast Ohio on 11/27/2012. No issues at all. BTW, it currently is on their approved list. Their tech people don't know off hand what is supported - they actually asked me if it was listed or not (which it is.)
Any DOCSIS 2.0 or DOCSIS 3.0 device should work on any TWC system. You will have to call their technical department to have the MAC swapped on your account. Once that happens, they will update your modem with their bin file and you will be up and running. There is at least one review of successful deployment of this device at TWC Raleigh.
You may want to confirm that DOCSIS 2 is still supported as most cable companies are retooling to DOCSIS 3. Older DOCSIS 2 modems will NOT work properly. This is what has prompted me to purchase the Motorola SB 6121 unit. My former Motorola SB5120 was incredibly stable for years until the last few days when speeds would dwindle to a crawl of 126 kbs and the connections would disappear.