The FM is pleasantly light. My unit has also some quality issues: two spots on the bottom scratched the mousepad - additional mousefeet helped and the right mouse button is ~0.5-1 mm higher than the LMB. Due to the tention (it looks like the stick that activates the switch is 0.5-1 mm too long) the RMB is easier to activate and has less button travel. Apart of that, the shell feels solid and the shape workes for me with fingertip grip.
The mainbuttons react with a tiny bit delay, i can not confirm 100% (did not want to void gurarantee..). Atleast in comparison to g100s/g302.
However I have decided to sent my Finalmouse back. The reason for this is mainly sensor surface compatibility/price ratio, even though mousetester shows no problems (see below). Just like the Savu, the FM is very picky and tbh it worked good with only one pad (Razer Destructor). With the rest of the pads the FM feels like it does not track seamless.
Warning: Spoiler! (Click to show)
I would give the Finalmouse another try once the final version is released and it is available in Europe.
Edited by Thunderbringer - 2/28/15 at 1:59pm