Dishes are desigened for either eatern or western arcs... From what I understand, That said a western Arc Dish MAY work on both but you may loose a few channels.
Since I do not (At this time) have DishNetwork, I am not sure.
Domes: (And portables like the winegard Pathfinder X2) work very well with a single VIP-211 since it is a single channel device, but if you have two of them, or a multi-channel DVR. you have a problem.
Finally Mounted (roof top) or portable
If you park among trees a portable may be able to "Connect" when a roof top would be blocked.. but rooftops are easier to "Set up" (push a button and you are done)
My recommendation is one of each and a A(bove)/B(elow) switch.