Actual required modem specs?

Hi folks, I'm getting xfinity 1Gbps service installed next week, and I'm trying to determine whether my existing modem/router combo - an Arris DG3450 - will work. I realize it's not on the list, since it's out of production, but the specs seem compatible - DOCSIS 3.1, up to 5 Gbps. Are there other specs I need to know? I don't want to be up the creek when the installer arrives, but I don't want to needlessly spend a few hundred bucks either. Thanks!