Only the Winegard Trav'ler gets all three DirecTv satellites to provide an HD signal. I've done it both ways and the Trav'ler is the way to go. Push button and it does all the rest.
One other point is if you have multiple TV's, using the HR44 or equivalent GENIE box allows you to get a different program on each of your TV's. With the SD boxes all TV's watch the same program.
If you go Genie and use the wireless Mini-Genie receivers at the TV's you can by-pass your RV's coax system as they use an HDMI cable. Really an easy system to use.