What about a mixed system: Delegates have to put up a tendermint like (http://tendermint.com/docs/tendermint.pdf
) collateral which is destroyed when someone signs a block on more than one chain. Either the Top 100 security delegates would have to all put up the same collateral hard coded into the client or the amount of collateral could be a factor besides shareholder approval (effect could be capped for example at 500% above average collateral among the top 101 delegates).
That would probably only work at scale when the competition among delegates is higher. The overall idea
is to rely on different consensus mechanisms to increase the overall network resilience. An idea I like better
than the above because it suffers less from what Bytemaster criticizes in his blog about non delegated POS: Among the 101 delegates could be 10 that are not determined by shareholder approval but by stake size. Because it are 10 fixed positions that all get the same returns from their position the problem described in BM's post about the centralization of POS doesn't apply. The problem here would be instead that 10 stakeholders with considerable stake would have to be found that are also able to run a delegate.
The advantage would be that every 100 seconds there was someone producing a block that had a direct material interest in the security of the network as compared to delegates who may "only" have an interest in keeping up their reputation and being reelected. Variation
: Instead of stake being the determining factor for selecting the 10 positions height of collateral (tendermint idea) could be considered. Not sure how this would play out.
I asked a few questions on the tendermint forum (based on the concerns that lead to DPOS) http://forum.tendermint.com/t/questions-on-tendermint/42/2 Regarding voter apathy
: Assuming voter apathy is the biggest challenge in DPOS wouldn't it be worth it to make "vote as delegates recommend" the only option? Disadvantage: Reduction (not loss) of anyway incomplete privacy. Logic: Network security comes first and has to work, otherwise the whole system including advancements in privacy aren't worth anything. The gains of individuals (privacy) shouldn't harm everyone (security).
Additional suggestion: If one of the 10 delegates changes their recommendations / slate then my vote should change too otherwise slates can not react fast and vote an evil / unreliable delegate out.
Alternative: Every week my client performs a transaction of my whole stake to myself so to confirm that I still vote as the slates I approved. A concern with slate voting (RDPOS)
: If I vote for 4 slates and all of these slates have delegate XY on their slate. Then XY turns out to be evil or unreliable and 3 of the 4 delegates I approved take XY of their slate then I still fully approve XY. Any solutions to that?
 I assume "vote as delegates recommend" works like this: You vote say for 50 delegates. If 10 of them have a slate with other delegates they recommend, then you vote for these 10 plus all their recommended delegates. Plus you vote for the 40 delegates that do not have a slate. Maybe this: If more than 50% of the slates I approve actively disapprove (downvote button) delegate xy than my overall vote is negative for delegate xy is negative.