The sustainability part is not a problem if Inleo is getting more than 22% value, if they get 30 and pay 22, it's sustainable for both the community and the maintenance of the site.

Regarding the curation by leo.voter, there is plenty of ways to get curation, since delegating already gives you an APR that is a good return. You have to create quality posts and use the UI, that is the way of getting curation.

Although, if you are getting the 22% APR it is because you are a premium user, so yeah, you will be getting the perks the premium users have and that includes a better curation %, as long as the post are made from Inleo and are quality content.