Behrens is probably 2 years minimum from being an impact player for the Avs. The window is now and this year is crucial. If they can snag a piece of the puzzle for years to come then yes, trade him.
I'm just really concerned about our cap situation. We've got over 30M locked in NMCs next season (Landy 7M, MacK 12.6M, Nuke 6.125M, Manson 4.5M). That doesn't include Cale's 9M (how did he not get an NMC?) or Rant's 9.25M. On top of that we've got Byram to resign, Girard taking 5M, and Toews taking 4.1 until the end of next season.
Still not sure Girard has the perceived value to bring in a 2C as the main piece. But in order to get a long term upgrade to JTC at 2C, we will simply have to lose one of Rants, Toews, Byram, or Girard. (I'm willing to bet nobody myself included actually thinks Rants is the right answer). If this is the case Behrens would be safe because we are already sending a really good dman.
However, if looking at a rental, you take the cap situation and combine that with the uncertainty regarding Byram's health and our ability (and frankly desire if his play continues to dip) to re-sign Toews. We are going to need dmen in the next few years. The question is, can Behren's be that player in that timeline. Because if he can, I think he's more important to us than he would be in a trade. I think he and Foudy would be the two prospects I would be giving a lot of pause to before including them in a trade this spring. I would not be pulling the trigger for a double and would be seriously hesitant on a triple. You've got to absolutely nail it if you are giving up one of these two guys from your meager prospect pool.