I received an email from AGR promoting the new card; the email includes a statement that there is now no limit on the number of TQPs that can be earned by spending $5,000. The previous limit was 4,000 TQPs.
When buying a ticket on Amtrak.com this morning, there was an offer for 20,000 AGR points and a $100 statement credit for the Preferred card. The 30,000 point offer above is much better.