Personally I believe that you shouldn't be able to trade materials for marks, it was nice while it lasted and I traded a lot for the marks but it should be the way it is now. If you need crucible marks play crucible, if you need vanguard play strikes. Simple. The only thing I could see being good for trading mats for would be rep for different factions at a 1 to 1 or 1 to 5 ratio. Ex. 1 spin metal gives for 5 rep for whoever your trading with. If not rep, at least some ammo synths or glimmer...just give us something to trade our mats for bungie!