But we don't get real differentiation to show us them being totally awesome. I was waiting for it! Visually and plot-wise the invasion seemed like it succeeded because of surprise, chicanery (ahem... you know what I mean), and overwhelming force. There was never a moment visually when I remember seeing the Sarduakar do something impressive ... not even in comparison to the Harkonnen.
....maybe that one scene where the Harkonnen troops were advancing, and the Sarduakar landed behind, but it didn't work for me. I just never saw/felt their relative strength. Heck, Aquaman was taking them out with no problem.