After playing with the FK for one week now, including two long 6h sessions on the weekend I can say that the FK has succesfully taken the place as my main mouse. Performance wise I see no difference in-game compared to the Savu, but the shape of the FK doesn't give me pain in my pinky after extended use.
I also feel no input lag at 450 dpi contrary to what others seem to experience. Max tracking speed is also fine being around 3.2 m/s on 450dpi and 500 Hz. It would be a bit higher on 2300 dpi, but then it'd get slightly jittery even on the NP+ (and a lot on the Talent) so I stick with 450. The LOD is extremely low as anyone already knows, but that didn't trouble me at all. I was afraid I'd get skipping from lifting it just a bit while swiping, but apparently I don't do that. I think after getting used to that low LOD it will be hard to get used to a higher LOD again.
Gripwise palming it is fine for my, this is the first ambidextrous mouse for me where I actually have no problems at all with the sidebuttons on the right side, they are between my fingers and I don't even notice them. The surface feels good, I like the coating/material a lot more than the grainy one on the Savu. Build quality in general seems very good on the one I got.
I actually like the Huano switches in the FK, granted I only play FPS. They don't feel hard to press though, so I think I would be fine with them for anything.
The scroll wheel is probably the only thing I'd like to have exchanged, because I don't use the scroll wheel for gaming at all other than pressing it. So the scrolling for me only is important for browsing etc. and there it is kind of tiring because of the big indents/low scrolling speed. Minor issue though.
Another thing I was worrying about was the thin mousefeet, because I had a lot of trouble with my Abyssus where the mouse would scratch the pads somehow. The FK however glides smoothly on any pad I tested it on (Qck+, Talent, NP+), perfect for me. The cable is probably the best I've seen in a long time on any mouse (this is my first Zowie...), much prefer this to braided ones and it is also more flexible than the ones on Logitech mice (G400, G100s).
This is pretty much the mouse I was wishing for, the complete package. I even love the looks of it, clean and simple, without flashy LED bull**it, and that black and yellow just looks nice.