DIAMOND is only really valuable if considered in the context of your future travel plans. For example: lots of international travel in locations with Hiltons and Conrads; Diamond status is invaluable.
If you travel plans only include Hamptons and HGIs within the USA, then you have to put a value on the free breakfast at the HGIs and the cookies and water at the Hamptons.
Personally I would not "throw away" $450 in the way thay you describe.
Just my view