Just arrived. And it's oh so pretty....And the ceramic feet on it are just amazing. Glides like crazy. Although since I only use aluminum mouse pads, I wonder if that'll cause an issue down the road. Regardless...sensor swapping in this thing is easy as hell. Would take like 5 seconds. Only complaint I have is that it now only supports 3 different DPI settings, as opposed to 4. And as a result, they've removed the option to go up/down. It's a one button that just cycles through them.
Also one area of concern....the scroll wheel. Very neat design. Solid click per rotation. No half-way rotations. But...it's also only latched down at a single side point (not central), which means more stress on it than there should be. And unfortunately that is not one of the parts that can be swapped out. So it may be problematic later on.
Another issue is with the way the mouse back/forward buttons work. Since that piece is replaceable, they've designed it so there are little plastic feet that fit into/push the actual button on the main body. However...as it is plastic and only secured with 1 screw, you end up with a situation where the amount of force required to activate the forward button and back button differ. And in fact, one of them is very soft, while the other has a loud and crisp click sound. For all I know though, this could be part of the design. But it seems odd..
Another oddity...for something heralded as the world's most customizable mouse, it's missing yet another set of customizations that were available in the RAT 7/9. Weight adjustment. There is no way to adjust the weight of the device. I'm pretty ok with where the weight is. But I wouldn't have minded it being a tad heavier.
Due to these things being sold out everywhere, I was only able to get my hands on the PIXART ADNS-9800 sensor. I'll have to game with it some more before determining how I feel about it. But as far as tracking goes, this sensor does work well on a surface than my old RAT9 with the 6200dpi phillips twin-eye sensor had trouble with. When the 8200DPI Philips twin-eye module is available, I'll be picking that up as well.
I really do like how easy it is to swap out sensors. And overall I'm happy with the mouse. But I definitely get the feeling that the customizations that are missing right now will be added/addressed in a 2nd generation model.