Is ARRIS TG1682G a supported modem/router, or not?

I was looking at supported modems/routers and ARRIS TG1682G is listed. In fact, it's the modem/router I'm renting from Xfinity right now, but with the Xfinity logo. However, I wonder if I can actually purchase a used one, and use it following two reasons:

1. It's not listed here: https://forums.xfinity.com/t5/Your-Home-Network/Approved-Xfinity-Modems-and-Gateways/td-p/3109887

2. An ebay listing for an ARRIS TG1682G stated "NOT Approved for XFINITY COMCAST."

How can this be? Now I'm afraid to purchase from the list Xfinity indicated are compatible modem/router combos..