I don't see the curve empowering big abusers and self-voting whales, they already have high power regardless. Any effect of the curve on them is negligible (few percent maybe).
The positives and negatives on small accounts and small votes are more debatable but this doesn't seem to be a large stake circle/whale issue at all.
I did a round of tests, and the results for when the threshold is reached are indeed lower than my subjective impression so far. A few percent of a high vote still translate in quite a lot of small votes, and when they had higher values the bigger ones would go down some more than the curve effect boosts them right now. It's still just a few percent, but that doesn't invalidate that it's on the back of the small ones.
My focus certainly is on the lower end, where it has the big impact.