Rick, yes, I am using a DMK41. I really like it for imaging the moon. It's very straightforward to use and, with my humble 10' dobs, it gives good results (my Astrobin gallery is available here:
http://www.astrobin.com/users/EricB/. All pictures except for the 1st one were taken with the DMK41. Please bear in mind that I am a beginner).
I can't really comment on the DMK51, except to say that that the resolution is, at least in my case, often impaired, by below average imaging conditions. So, on a practical level, I am not sure the extra step in high resolution makes a huge difference. I am sure other members will offered more informed comments.
In any case, I would prefer to use a CCD camera over a DSLR to image the Moon. Others may disagree with me.
Cheers,
Eric