The dealers telling
The dealers telling you 6 months means they have no idea if they will ever get an order for a '09 MMH for you at X Plan. Why should they give you one of their few allotted units at a price they could get far above? On the other hand, there are dealerships who will sell the few allotted units at X Plan just to get an order now as a retail buyer in hand. A stock unit for the lot is limited now in many areas of the Country, so some dealers can only order with a retail buyer order X plan or not. My dealer was up front, none of his allotted units was going to be sold as X Plan. Many other people did get X Plan and their unit is being built and shipped as we speak.
I would go with the 6-8 week dealers and monitor the building progress closely. In other words, 6 months may never happen.