Hi Hoot,
I can attest to Bob getting to and from Muir in under two hours - he did it when Carine and I were on the summit watching him!
To compare the MR with Colorado peaks - The Final 400 above the notch on the MR is sort of like a longer and slightly steeper version of the Crestone Needle gulley or the last part on Wetterhorn but with larger slabs.
The ramp/chute up from Iceberg lake, at least in snow, is on moderate angle snow which steepens a bit higher up, it does get softer sooner than above that since it faces east and gets the morning sun.
