If it were up to me I would change a few things. I am not a fan of the "ghost and goblins" style scaling of basically trying to make difficult by mostly scaling up damage and getting 1-2 hits kill a lot of players.
I would make it more like hardcore, above R6, you die you get kicked to your bind point and the party goes on without you. I actually think that would be much more challenging. I would also though change a few things with reaper.
1. Tune down mob damage
2. Get rid of the bonus hit points so it is easier to balance across reaper points
3. R6+ you die you are out of the quest
4. Get rid of self healing penalty
5. Increase minimum CC duration to 12s, to allow for more strategy and things like Earthquake/Otto Ball to be relevant in R10.