I'm ok with as low as 4 weeks but not lower. There is certainly a lot of people who will not power up (or powers up less) due to the large risk of a 13-week power down. On the other hand, it will encourage more powering down and dumping. No one knows which will be more common.
With the changes to curation, we have already seen more powering up.
I'm not going to vote the silly proposal though.
RE: HF Proposal: Vote to Reduce Power Down Period to 4 Weeks