Yes, it's absolutely essential that a switch to a nonoutsourceable puzzle also comes along with a variance reduction mechanism. I have no clear winning solutio

Yes, it's absolutely essential that a switch to a nonoutsourceable puzzle also comes along with a variance reduction mechanism. I have no clear winning solution for this part, but I've got a few ideas and have discussed them with Peter Todd, who also has ideas here. Basically the approach should be to internalize P2Pool, and to let miners choose a lower difficulty if they want (for a proportionally lower portion of the reward). This is really subtle though. It would increase the amount of bandwidth needed. It would be easier to discourage / punish a block that has less difficulty. Also, some component of the reward should still be a high-variance jackpot... the nonoutsourceable puzzle is only effective when there's a luck component, and thus a big incentive for the real worker to defect. So there's a ton more work to do. It's definitely not time for an immediate hard fork. But the discussion should begin.