I've flown through AMS quite a bit but only last year as DM. There are threads with pages upon pages of what a hot mess ex-AMS seems to be.
Before I was a medallion, probably not even collecting miles, there was a period where every time I asked the gate agents for an upgrade I received one. That was before introduction of D1. I am 6'7", and look Dutch, so it could have had a part in it.
Last year I waitlisted AMS-SEA and had a hell of a time getting the upgrade to clear. The lounge was very unhelpful. Finally a gate agent upgraded me and without taking my GUC. Can't really complain there.
The possibility of getting a 200 EUR plus 35k D1 upgrade always enticed me but was never successful. I think I'd rather have Delta clean it up, to make it more consistent if possible. I'll buy D1 if reasonable, but last minute 10k USD prices are not and that's when GUC or USD upgrades are great.