I think the idea of 50/50 rewards impacting self-votes and circle jerking is delusional.
Be whale.
Have 2 accounts.
Use one to upvote the other.
Keep both sides of the spread regardless of the splits.
A circle jerking arrangement will be sightly more complicated, but it follows the same principle.
Changing the rewards split will impact the bid bots and the curation trails.
Yeah the problem with curation abuse is it is harder to detect, post abuse is easy to spot cause it goes up on trending and the author is blamed for selfvoting, with curation it's harder to point fingers and detect, and yeah they just vote with several accounts and gain the required rewards, I mean I could make a post with one account and split my stake to 10 accounts and upvote my post with it. Luckily I run a business on Steem and have no time or interest in doing such things.