Personally for CoA H I would recommend these changes for the RM fight:
*Spawn Leo when RM is aggro'd, then spawn the following turtles at 2 minutes, 4 minutes, 5 minutes in.
So Leo --> 2:00 Miki ---> 4:00 Donna ---> 5:00 Raffi (the last 1 minute jump is to hold onto that hard mode "chaos" effect)
*Extend Ratmaster's "Invincible Sleep" duration to 7 minutes rather than reducing it to 2 minutes.
*Extend Ratmaster's Enrage Timer to 18 minutes. -- This will technically give you 11 minutes (not counting all the stuns and other BS) to hit the 2.6 mil damage mark after he wakes up and can take damage.
To compare to the current pre-patch enrage timer, you technically have 10 minutes to hit the 2.6 mil damage mark (from when Ratmaster wakes up and can be damaged).
Basically I'm asking for 1 more minute on the active enrage timer.
OR, do not start his 12 - 14 minute enrage timer until he wakes up. (I think this was originally intended due to the CoA N "Kill RM in 8 minutes!" khara challenge, which starts the timer while he's invincible, only giving you 4 actual minutes to deal 2 million damage ((this is impossible)) ).
*Change the way energy cores work -- Unless it was intended for RM to always have a 120% damage buff that you have no way to dispell. (Actually wondering about this)
I think doing it that way would better fit the "speed run" theme since you would still follow the goal of focusing the turtles down to sleep before actually facing RM (which is actually do-able in CoA N), yet still maintain some of that "chaos" by having raffi spawn quickly near the end.
I don't believe in giving everyone huge HP buffs and nerfing all of his damage-- I just believe in giving people some extra time to kill the turtles before fighting him. I think that kind of change would make the fight more realistic and at the same time keep it difficult.