from my recent experiences (some of which described here on FT before), I think they do often treat non-CX Emerald's even better than their own CX DM. so I'm keeping my DM really mostly so that I can use my miles...otherwise, in terms of service, I don't really see any too strong benefits of being DM vs. non-CX Emeralds...and that's also why once I reach DM every year, I start putting my miles to AAdv for the 100% bonus and lifetime status.