An alternative consideration: If you don't go for DM, the extra rollover MQM's after 75K deduction for platinum will help you qualify for the 2025 status (10:1 conversion to head-start MQD's). If this matches your travel plans and chances to get 15K MQD's next year. (2x Amex cards gets you 5K MQD's)
Being DM for a year and than dropping to Silver or to nothing at all won't be satisfying in my opinion