In Oct 06, I went with a group of 10 people. We booked through Small World Vacations and were never told that we were a large enough group to qualify for a "grand gathering." All of our reservations were linked in the system, but we were offered no opportunities for "extras."
I recently booked a trip on my own (without
travel agent) for 13 people in Nov 07, and was told to book the trip as a group - therefore qualifying as a "grand gathering." Each family still has their own individual reservation number but we also have a grand gathering groups reservation number. I have to say that this has been awesome! We were immediately told of the extra events only available to grand gatherings. Granted, these experiences cost extra, but they sound wonderful...and magical! Also, we have been directed to group dining for all our ADRs. This was great also! My DSisIL had called earlier, before we were a grand gathering, and tried to get ADRs with no success. However, once I got on the line with group dining, some (though not all) of our options seemed to open up a little bit.
I would definitely recommend booking as a group. There really is no difference in the individual reservations or in how you can pay for the trip. No one ever told me that one person would have to pay for the entire group. There are only plusses as far as I can see.
Have a great time with your group!!!!!!!!!