I have been using the standard Night Stalker for exactly 3 years. It has not given me any trouble at all. Well, one of the metal foot pieces did come off, but I found it later in my toolbox on the truck, and has not given any problem since.
If I did most of my hunting standing, I would probably go with the Pro model as it should add some stability, but I have made shots to 377 yds. standing with the standard model. Direct attach with a Arca Swiss plate works much better than the Saddle, but I keep the Saddle in the truck so that I can attach any configuration as a back-up.