In their current form, 100% yes. The part of the proposal that is really hard to have a discussion about is expected user behavior. It is impossible to predict, and everyone has their own opinions based on subjective biases.
The goal is to change the mentality behind downvotes, where they are no longer seen as an attack. Instead, the hope is that they will just become a normal part of the platform (similar to a thumbs down on YouTube). Of course it will be different when money is involved, and of course there will still be cases of abuse. The hope though is that the benefits outweigh the cons - which we won’t really know until we try.
In the worst case scenario - if things totally go to shit, then we do have the option to roll it back or even eliminate them entirely. It all boils down to what the stakeholders/community think is the best path forward.
RE: Hardfork 21 - Steem Proposal System (SPS) + Economic Improvement Proposal (EIP)