Thank you for your response and explanation. I think it would be helpful to know when the request response investigation has been initiated, even if an actual answer is not immediately available. Perhaps a "status update" every six hours (or less)... to confirm that it is still under consideration... and any progress that might have been made. It would help to alleviate some of the anxiety caused by not knowing whether or not the issue is even being considered.
I appreciate that when you can reach DH support they are pretty straightforward and that they don't BS their customers, even if that might be the "easy" thing to do when an answer isn't achievable without a little more work.
BTW, I like the concept of the DH Wiki, and think that would be a great place to expand on specific topics like the one I've raised here. There is a brief mention of MX records, but it is somewhat abstract and doesn't deal with the nitty gritty of how it works on your servers... in my case the key detail is knowing you have to "disable mail services" before you manually install you MX and A records. Kind of counter-intuitive unless you've already done it a few times :}
P.S. I've tried to clarify my question in the other thread... if you have amoment to look it over and respond. Thanks.