I would think that Pavelec is a legit keeper in any league format. He played in 58 games last year, even if he missed the entire first month of the season. He dosn't have any serious competition right now, and there isn't a prospect in the minors who seems capable of stealing his job anytime soon. In Winnipeg, the D isn't overly impressive, but the team in general will get better every season. New GM will have money to spend, but seems willing to wait and give a chance to all of the prospects to mature, and then proceed to improve the team with free agents. His SV% is already respectable, the games started will icrease, so will the wins. The down side is that I don't think that the D is impressive enough to expect a lot of SO.
I think that Pavelec holds more value than Mason and Varlamov. I don't like what Sherman is doing in Colorado, and Varlamov is injury-proned. With the contract he just signed, the #1 spot is his to lose, but Giguère could very well carry the load if he falters.
I am a big Mason doubter...and a Columbus doubter as well. I don't expect Wisniewski and Martinek to improve their overall D at all. The acquisition of Carter might help them score goals, which could ease the pressure on Mason, but he seems so fragile and lost right now that I would not risk to keep him, especially over Pavelec.