swapping the dish on top to the winguard t4,motion

The difference between Dish and DTV is that if/when Dish drops the SD feeds, the dome antennas will still work for all channels. When DTV drops it, there may be only a limited selection of channels available with a dome. All SD only receivers will be obsolete of course for both services.

As long as you can switch to Dish later....from all reports Direct TV won't be supporting Standard Definition Receivers much longer. Dish may not be too far behind on Standard Def. I have two older Dishes on my RV, an in motion and a real old Datron system, both Direct TV standard....so I see upgrades or service change in my future. The T-4 is not cheap...so buy carefully.