If we're getting rid of EE, then I'm all for adding this. And the costs are pretty fair. Iron chest = 2 wooden chests, costs 1 wooden chest + 8 iron bars.
Gold chest = 3 wooden chests, costs 1 iron chest + 8 gold bars
Diamond chest = 4 wooden chests, costs 1 gold chest + 8 diamonds.
Seems pretty fair to me!