Did not know it was originally 50/50. I think a lot of an author's material should be credited the bulk of the post earnings because they originated the discussion. Give it more importance. What comes out are people who simply click a upvote button once and get some credit if in fact others do the same. When a curator also posts a response often times readers will upvote those responses which in turn is a bigger reward for the curator. In short the 75 to 25 between author and curators seems fair.
Regarding the 30 min to 5 min upvote steemit I have no feelings about either choice. As long as there is some time delay so that upvote bots don't come in first and snatch most of the curator awards it is okay. I think steemit should have a better way to identify this timer to the users. Maybe have the upvote button be a different color until the time limit is up?