Have been in both and could be happy with both the main factor in deciding to go with the sierra which is the same as the sandpiper was the interior hight of the front cap and the slides. The sandpiper/sierra is a full profile unit and the interior height of the slides is more. If you are tall then you will hit your head a lot in the sabre. If you are under 6' then the interior height want matter.
2013 Sierra 355RE ( The Palace )
2012 Dodge Ram Crew Cab W/ 6.7 Cummins ( The Goat )
Me, the wife, 2 kids, 2 labs (they dont travel) and 1 Shih tzu (he does)