The main problem is destroy sometime a lot of items - 100/200 or even 400+ 'cos if u have a good party you catch every moment and can't go and finish quest.
So, maybe gold decision will be simple - make quest items Private WH Tradable - you will no need to worry about overlimit Q.Items and still can't sell or trade with someone - just store in your WH so much as you need, and take when you need it. No wasted_time_feeling with deleting items process and kept balance.
@Koll please take a look on such decision