I guess once what constitutes a "REDPOS" protocol is defined, then comes a specific implementation of such a protocol.

For a specific implementation you also would have to take into account not to brake the economics of that blockchain. If you in any way change how the Steem Power works in regards to rewards, you are actually defining money power as variating according to the holder (of that money power). It would be some sort of "tax" policy, but not a flat tax.

I think a competing blockchain offering "lower taxes" would prevail comparing to one with "higher taxes".