Another thought: Currently there's a problem with very large transfers, since guarding them against double-spending can take days (at least) of confirmations. Paying transaction fees won't help because it can only get it in a block faster, it can't significantly affect block generation rate afterwards.
With the new system (work/stake hybrid approach), senders of large amounts can include a signature fee in addition to the regular miner fee, which goes proportionally to stakeholders who sign the block in which the transaction appears. This will incentivize stakeholders to sign, making the transaction secure without having to wait for more confirmations.
I think a hybrid approach would only allow stakeholders to sign whole blocks that have already been found. And then miners could defer authority to the stakeholders when they do, and work forward from that block. This would decrease the confirmation time to 10 minutes on average. And it would remove the need for checkpoints, making Ben Laurie a happier camper.