I think the biggest problem related to any "voting-based" system is:

• Voting Apathy

A lot of people won't participate in the democratic process and do not hold the elected accountable for their actions. This not only leads to the problem that only relatively little stake is voting but also to the problem that once someone has a certain amount of votes he most likely won't be kicked out of the top 20 so quickly again.

• Transparency

While decisions in terms of hardfork and softfork are visible to the user a lot of the discussions surrounding it are not. We cannot see if the elected are doing what they should be doing.

I did outline in a post of mine ideas how voting apathy could be combated. And, as soon as we got people participating in the democratic process, forcing the elected to be transparent becomes a solvable problem.