I'd be more in favor of a 1-2 week power down time. That's what's needed to prevent double voting on content with the same stake.
Apart from that, there are two concerns motivating the lower power down time:

1. Security against hacks. In this case we can either live with 1-2 weeks as good enough hacking protecting, and already better than most cryptos (and already more than deemed acceptable by the savings feature), or add a power down lock feature to accounts which takes longer to clear (say 30 days to align with account recovery)
2. Governance voting, to ensure that longer-term holders decide on the direction of the chain, not short term speculators or attackers. We already address this (which was not the case prior to a recent update) with a 30 day delay on voting by new stake, which could even be increased.

Whatever economic benefits allegedly derive from the longer power down time (I guess slower powering down and selling) are likely offset at least to a large degree, and possibly more than 100%, by reduced buying and powering up.

I would propose 1-2 weeks, leaning toward 1 week, or even 5 days.