I was wondering how you were going to address spam. The obvious solution is having to burn a fee to post and I think you will eventually be forced to use it. This proposed solution seems like it can be gamed to hurt innocent users or suppress speech. There doesn't seem to be a real good solution either way from the pros and cons, though.
I would donate a steem per week to an effort to track, find, and castrate spammers but I agree that the "solutions" mentioned above will likely end up being censorship tools.
Note paying to post won't solve the problem if the spammer or content thief can earn more from the activity than they must pay. Already the system charges in some sense because the poster need to hold sufficient stake in order to have the bandwidth allowance to post.
I'm thinking to make this thing workable, actual main topic posts would require a fee to post, while comments would not, but comments would also be culled off the chain eventually.
Increasing the number of clicks required to access content is not censorship!
Anybody who has truly been censored realizes this.