DOCSIS 3.0?

When shopping for a new cable modem, is it pointless to look at DOCSIS 3.0 modems? Are they still accepted?

Currently have a SB6183, rated at 683mbps but limited by Xfinity to only get to 300mbps.

Netgear CM600 has come down in price and rated at 960mbps, 959 by Xfinity. But only a DOCSIS 3.0.