I read @fyrstikken's post about this and now yours. I am at a point now where I am convinced that 50/50 may be the way to go.
Although it doesn't really stop shit posters from upvoting themselves from another account, it will certainly make things better for people like me who love to actually read and curate.
Especially since I am continually buying more SP yet keep seeing my investment value drop. With a higher curation reward it may help to offset that.
50/50 alone won't stop it, but in addition with a downvote-pool (meaning you would have seperate voting mana for downvotes), spammers could be easily countered.