Satellite mounted dish - Autoskew or not??

Tammygirl

Which is the best dish/system to have fitted to a motorhome. We do have a freestanding one but the OH is fancying a roof mounted one. It would need to be an 85cm as we tour across the water, we thought of a twin LNB with autoskew but do we need autoskew?
 what are the advantages. Would be grateful for comments from those who have knowledge of them.