I just want whichever one has a smoother sensor
Again, what the hell do you mean by "smooth" sensor? Usually "smooth" is not something one would want for a gaming grade mouse. It doesn't feel raw, or 1:1, rather filtered/enhanced, with a variable degree of input lag, and/ or prediction. If that's actually what you're after, the Taipan's input is "smoothed" quite a bit for instance. That doesn't make it any less precise though. Seeing that you used an optical mouse until now though, you will notice a difference with both the Sensei, and the Taipan. For gaming the 9500 (Sensei) is the lesser of two evils, and for desktop/office/editing/whatever have you, both the 9500, and the 9800 (Taipan) are perfectly fine sensors, with the Sensei being quite a bit larger. Both mice are quite heavily marketed, so it shouldn't be a problem to try their shape. I see them in pretty much any electronics store.