The only fly in the ointment might be your existing antenna on the RV. If you're using a dome, it is probably compatible with either service. The only thing is it'll have to be reprogrammed for Dish, but that gets you HD with a single LNB antenna. If you use a tripod, you'll be fine with just a new satellite antenna which you can find for little or no cost.
The package you're looking at is the same one I'm on. I've never bothered with DNS because I don't watch local channels enough to bother. Buying your own equipment might save a couple of bucks a month, so I'm not sure it's worth doing. I own one and use four of theirs. Looking at my bill, there is a $3 difference between the owned receiver and the others.