I've been eyeing the M-D ever since it came out. I could technically afford it after selling my M Typ 240 but I don't know if I can justify it yet since my M has exactly the same sensor (essentially).
I covered up my M's display about two months ago and have NOT missed it at all. In fact, I'd say my ability to previsualise my photographs has improved slightly because of it, and not only that, my mistakes have been more impactful and a better lesson learned after getting home and finding an exposure or whatever was off. I've been employing the film-zen method of taking pictures for a little while now and it makes me enjoy photography even more. I'll definitely be considering it in the near future as a replacement to my now "blind" M 240.
By "film zen" I mean, look first, expose, focus and compose, consider the frame and only then click the shutter (once!). No spray and pray. Nowadays I'm "Making" every frame, not hoping to get it right. I have to make it right.