We own 2 Westin properties and in 2020 thought buying 1,500 DP with Marriott would help bridge our ownerships. We just went to Marriott update last week and they tried to convince us we should buy 1500 more DP points to jump to next level the break down they offered us 4500 one time points- 1500 yearly DP after discounts etc. for $17,640. Bottom line we turned it down.
Our WKV 81,000- is 2,850 marriott- our WRF 95,700 is 2,250 marriott- our Sheraton 44,000 is 900 Marriott- i doubt we would ever change over to use the marriott properties with those- We have however enjoyed using our Marriott DP for 5 night get aways (Hilton Head- Myrtle Beach- going to Frenchman's cove in Nov) Everyone's travel needs are different, Good Luck with your decision.