For what it’s worth -
stayed at the Rockwall Hilton last night. Booked a normal king room, no early indication of an upgrade etc. I didn’t care. However upon check in, we were upgraded to the King Suite with Balcony. I saw they were available on the site for around $400 more than I paid. So it seems like it’s not effecting upgrades when available for diamonds. and there was a MASSIVE event at the resort that night.