Its nationwide atleast with the DNS facilities having to resort to using lnbfs other than the DPT and DPPT though they are only using them in the case of customer saves is what is being discussed in the installer zone ( another section that you can find here in satelliteguys.us )
Nothings being said as to why Dish is holding back on the use of the twins but there are a few instances of history that can lend to the reason's why.
Dish in the past has wanted come across storage units / containers in warehouses full of legacy equipment and they send them to the regional hubs and then onto the dns offices to push them out, in the process of doing this each office is informed to use the legacy equipment first and most of the legacy equipment thats going to these offices is refurbished items.
Dish also will push legacy equipment and horde newer DP and DPP equipment when there is something big in the works coming up such as a conversion or channel roll out requiring a wing dish or new dish type, a good example was with the 129 dish 1000 when it came out or rather before it. Dish had its offices hold back the DPPT's, DPD's, DPP44's, DP21's, and DPQ's and pushed facilities to use legacy equipment as much as possible, they later added the DP34 to this as well and it really created alot of havok.