The effects you mention are mostly true but you don't account for the slider which can undo the change for active curators.
Most importantly this takes power from the whales
Whales are almost always at 100 percent voting power in the current 40 vote system. I haven't run the numbers but I suspect they were getting 90 percent of curation rewards. Under 5 vote system they will often be voting with less voting power.
If they average 90 percent now and my 90 percent guess was right that means the other curators will get an incremental 9 percent of total curation rewards.
The 'slider' is reducing users voting power. A 20% vote, is voting with 20% of a users voting power. Thus, 20% of the rewards that a 100% vote would receive, and 20% of the rewards allocation the beneficiary receives. They can spread their votes out more (correct), however overall, it does not impact the curation rewards, or the influence a user has on the Steemit Platform.
I didn't account for this, because the net impact of the slider is zero. It's only a means for spreading voting power. Active users are now spreading a lower level of voting power.
From my experience, over the past few weeks, most 'Whale' votes I have seen have been below 100%. See here
Yes. For most purposes, voting at 20% to keep voting power full and voting full power while hovering around 20% means about the same. I analyzed it recently.