Montembault has tons of room to grow, and I think it's perfect. He can be THE starter - play the games, play to win - and if he can take his game to the level you describe, he's a great gatekeeper to the starting spot, so Fowler or whoever wants to challenge him has to be better than that. For this particular situation, I think all of our goalies are being given great growth opportunities and appear to properly sheltered.
Monty is best to be a starter
Primeau a backup
Fowler and others in their respective levels