It really depends on who is playing in each. In fact, it might depend on what point of the game it is. If a low ranked CFP team looks like they'll get demolished, I might watch for a few minutes until it's confirmed, then switch.
Absolutely. I like the NFL, but it's a team I have no affiliation with besides I like the team. I went to my college, I had classes with the players, and spent 4 years of my life "in" the organization, and a few more living in the town. It's not even close for me. If my NFL team is playing, I'll second screen it and it'll be on mute for my CFB team.
I can only speak for myself, but I find college games more entertaining than NFL games. I wonder how this will actually play out. I'm guessing it will depend heavily on which teams/fan bases are matches up in those games.