Seems like a solid plan! Can you give more details about the reputation algorithm you plan to use? The STEEM reputation is kinda bad, but there are alternatives like steem-ua

Anyway I hope you don't ICO for a project like this. Give yourself some tokens and create value and utility and I think it will be more worth it for you in the long run for your project.

Finally, the 80/20 split choice seems like a terrible one. Curation is actually very important, if you are going to 80/20 it, why even bother with the 20% as curation will never be an interesting thing to do anyway in your platform?