Just booked an award stay and the rep told me that on May 22, Hyatt is rolling out two benefits that will make Diamonds jump for joy:

Guaranteed rooms with a 72-hour reservation
and
No blackouts/capacity controls on award stays (with a premium for when they are in "capacity control" mode)

The property I was looking at was capacity controlled on one of the nights I wanted to stay, and I was advised to call back on May 22 and override it.

Thank you Hyatt! Thank you thank you thank you!

Now if I can get an account update more recent than February, it would be perfect.