I think it sounds reasonable for lowering the vote.
I have never lowered a vote, but, I have increased it, sometimes if they are new and there isn't much on their post. It's just a little booster or if I mistakenly don't make the slider go up enough and missed it, but, I lose my curation for this?
If you change your vote, you loose all potential curation rewards.
That's fair. It prevents trying to cheat the system. I'll get out of that habit and hit them another time.
Thanks!