Guhle is a superior player, bar none. Miller has struggled for two years now and Guhle isn't prone to the same mistakes. Guhle has been fantastic whether the team has been a tire fire or not. In any event, there aren't many player of Miller's profile either, as your small list has shown.
If you read what I said it was: "Other players like Lindholm, Sanheim and Brodin were almost untouchable for years". It took 9 years and him being a UFA, a first, a former first and a second to get him, as an impending UFA. This validates what I'm saying. Rare type of player who's rarely available and difficult to replace.
As far as Gavrikov goes, why would he sign with Montreal ? He's been in the US his whole career and there's no reason to think he'll go on a team that already has two LDs with prominent roles. If Montreal can sign anyone, then this discussion doesn't take place, because they'll just sign Bennett with the Gavrikov money right ? No need to trade a young player that's part of the core then. Reality is there are certain profiles that are rare and difficult to acquire. If you're trading them, you better make sure there's a low risk high upside return and a realistic plan that follows.