I had an 06 SXR and used it in the same way so I never installed a bilge pump in it either. The stock siphon did a great job on it's own but I added a duckbill anyways and found that it did a great job of getting out that last little bit of water out of the hull at the end of the day on the trailer. Since the stocker kept up before, I never noticed a difference when riding. Had the Versiplug R been available back then, I would have gone that route instead of the duckbill.
You don't ever see how much water a duckbill or versiplug flows when you are riding so it's hard to judge their effectiveness. Now that I flush my ski's at the end of a surf session and rinse my engine bay with water, I get to see how much water actually comes out and it's just a dribble compared to a scupper or bilge pump.