So my new backdated AMEX reported to TU. It's my oldest account (2 years), and my TU score increased by 28 points to 710 
Everything else remained the same. My AAOA went from 7 months to 9 months and CH went from 1 year to 2 years.
Congrats on that backdated Amex!
Boy, you've had quite the roller coaster ride this month! 