I also used the link and it worked the first time. We are arriving in November and departing in December. I didn't have any date issues. I received a confirmation email within the hour. Just waiting to see if it shows up on MDE. The link to the online form should really be posted in a sticky. Saves a phone call.
I called over a month ago to make a reservation adjustment, and they told me they would take care of adding DME to my reservation. But it never showed up under MDE, so I followed the link and gave them my info. I'm hopping it pops up sometime soon. I really don't want to have to call again.