As the game progresses ... especially with the rumor of lvl 25 reaching most ears as something planned for this year .. older raids become a drag .. repeating the same raid over and over for gear that is effectively made useless by epics.
While shroud weapons are not quite there yet ... its much easier to get a Antique greataxe epic then it is to get a min II ingredients and shards and blank weapon and and and and.
So why not use the revers refuge idea ... allow us to trade in three smalls for a random medium .. three mediums for a random large.
Keeping them random rather then selected .. prevents people from quickly obtaining large scales or stones (the more rare ingredients) easily ... but it means that having 100 small devil scales and 100 medium chains ... and a 100 large bones .. could lead to 1 large devil scale.
This means if you run 100 shrouds and only get 5 devil scales you can trade in the millions of other ingredients you have and MAYBE with a bit of luck get the larges you need to complete an item.
I think this conversion MUCH LIKE REAVERS should only be able to be done at the appropriate alter. Either on your gulid ship or in the shroud raid or amarath battlefield. But it would lessen the grind of a raid that is well past its "fun" date and well into its grind time.