Powering down to power up on HPUD is not a good idea. You just lose part of your curation reward.

Holding 10 Free HIVE in the account so that one has funds for Power-Up-Day has the same consequences.

Lets say a user made 10 HIVE in the first part of the month. It would be better to Power Up those 10 HIVE for two weeks, then power down seven days before HPUD.

Holding money in a cash account for power up day isn't a good idea either. The HIVE buyer would miss out on awards as well and will lose the ability to time the buy during the month.

Any decision one makes so that they have a specific amount of HIVE for HIVEPUD just loses curation rewards.

In other words, HIVEPUD, as it is designed, isn't accomplishing what we want it to do.

A better design might do something like give an award if the user went a month with power ups and no power downs ... or maybe it would sufficient to show month on month growth in HP.