So the idea I had, is to place an option on old level capped BCNMs to chose between either fighting it capped or uncapped. With the capped remaining unchanged or even an increase in drop rates to intice people and the uncapped having a reduction in drop rates do to the decreased difficulty. I would suggest 50%.

I.e. In which there would be an capped increase drop rate.
Item X has a drop rate 20% in a BCNM40. Playing this BCNM capped with other played would increase X's drop rate by say, 25%. Which would increase it from 20 to 25%. Playing the BCNM uncapped would decrease the drop rate by 50%, lowering the drop rate of item X to 10%.

Options like this would give players greater accessability to this older content especialy in light of the upcoming [DEV1018] update. It will also give new players more access to help from other players who other wise would not attempt these as they currently stand. Other things like assault have optional level caps as well, so the implementation to BCNMs should be viable.