Darn!
As a soon to be ex-DM I was considering routing my returns thru AMS to occasionally score an upgrade, as no more GUCs. I could still do than on KLM metal I guess but I like Delta's C+ (on 333) more than KLM's (usually on 747 Combi)
The last time I successfully got an upgrade it was for 35K Skymiles straight up (no copay). I was pleasantly surprised as I was expecting 25K SM plus €400 or so.
I was hoping try again on my trip last month but when I got to Schiphol I found I had been (non OpUp as Y was empty) upgraded already.