You might want to consider a more aggressive automatic weighting for delegates that become unavailable or that do not perform against basic metrics, like upgrading. I took my BTS+DVS delegates offline a few weeks back, not that the BTS one was ever in the 101 but still I see no change on the ranking of either of those.. which is slightly odd, given that those are not responding they should loose reliability weighting faster. There might be a risk of abuse via DDOS but I expect there will need to be DDOS protection deployed on real delegates anyhow.
Relying on voting.. compelling voters to be active, always seems like a weak link. Most BTS holders, most of the time will be busy doing more than attending to the politics of BitShares and then also voting to that.