Not a CC user but like everyone else the check out change is beyond annoying for us that are SPG Platinum but my ..... is around the change in earning stays.
I usually earn SPG platinum through stays and not total nights so the move to nights only with Marriott will be the factor for me moving most of my business around Hilton Diamond.
After hitting lifetime Gold this year my business will drop although I do like how Marriott tracks lifetime stays for credit though.