Manson for 4 and especially 5 years shouldn't even be discussed. $3.5m X3, or $4mx3 tops.
That isn't to say that I don't like him, I think he's doing a great job, but paying 30+ bottom 4 Dmen is how you get into cap trouble and forced to trade core players.
There should be some solid Dmen available relatively cheap who can fill that role. Also, don't discount the vets who want to chase a cup, which we saw to some extent with Murray last off-season; along with Cogliano, Helm, JJ, and Manson (who waived his partial NMC) among others who were all keen to join the Avs this year.