Very good points.
RCs system could remain as it is, with full capacity given instantly. I don't see why not.
For the error powerdown, we could make it 1 to 3 days, that would would give enough time for someone to realize the mistake. About the witness shuffling, we currently have the same issue when a whale powers up huge amounts, so it shouldn't be a big problem.
It is unlikely that a whale powers 100% of its stake down if it can powerdown 25% of its HP in one day.