A lot depends on which replacement coach we're talking about. Last I checked, Sean Payton isn't available. Neither are Arians or Harbaugh.
If we're talking a potential upgrade to the coach we already have, you consider it. I'm sure, though, that my list of who's likely to be a clear upgrade differs a lot from your own. That's where the rub comes in.
If we're talking Mike Mularkey, Jim Tomsula, Jay Gruden, or Mike Pettine, well, no thanks. Sean Payton is a really good coach. If he's available and you don't consider the move in Dallas, you're not doing your job as GM. He's got skins, a relationship with Romo already, he's liked by the organization and will come in with the respect of the locker room. Dallas is probably at the top of his list of potential vacancies if he shakes loose. The only questions I have about him myself regard the rumors of some of his personal problems, including the possible dependency issues, but that's a matter for the organization to look into themselves.
Then again, I don't believe the problems in Dallas are with the coaching staff right now. I'm perfectly content to see how the rest of the season plays out and to take it from there. Right now, Garrett's on fairly firm footing, but that could maybe change depending what happens when Tony comes back.