I agree with not having the power up tax at this point. All incentive should go to those who stay powered up from this I think, as while the burn is attractive as is the dao, I reckon this would be more effective to attract powering up of stake, which could make a significant difference.
I don't think this would be considered for the next HF, as I am pretty sure they are close to locking now.
Instead of a direct power up tax, I think an indirect power up tax should be considered. For instance, newly powered up Hive does not collect from the tax pool for say 90 days, or some length of time that everyone agrees on or that is a witness setting. It benefits current Hive Power holders because the tax that would have went to the new Hive power will go to them instead, which is basically the power up tax in reverse. The pain is not felt at the power up though so it doesn't seem as bad to me.
This would be interesting too, but perhaps not very attractive for new investors?