I don't think Free Downvoting is a good idea, Let's think differently.
There is too much quarreling around the free downvote.
There must be the responsibility on what we are doing.
But there are no room for asking the responsibility for the free downvoting.
The free downvote seems the privilege of the whales.
In ideal form, each account must have same free downvote mana, not relating to the amount of the SP, if it is free, in my opinion.
If the downvote is not free, then it seems be no problem that the downvoting mana allocated according to as much as they own SP.
My suggestion, if the free dowun vote is essential in the Steemit community, it is more useful that let ach account have same free downvote mana.