A lot of good ideas. In regard to the one thing that keep deep dungeons from being truly epic and engaging in my opinion, I especially do support that the mode needs a power progression feeling, because once you're past the leveling floors, there is no progression beyond floor difficulty, and it makes everything monotonous. Make us get crazy perks and don't hesitate to give us exotic things and buffs to play with.
As for my own hopes I've already summarized them
here.
( now watch them serve us Orthos reskinned with nothing more to it )