omg, you truly get down to 8,5 watts with Ubuntu 12.10? I found it incredible to get down to 12 watts, in the times of the alpha2 release when I bought my UX32VD the lowest I could get was 19 watts... I never looked at the windows power usage, I didn't even know that windows is capable of telling you the watts it takes out of the battery. Only thing I can tell about windows that it was horrible slow with all that bloatware.
To be honest, I also think that the battery time is quite horrible small with max 3 hours that I can currently get.
about the trackpad, I think its a fail on design and driver level, on windows it worked better. But I managed to get around with it by not removing the finger from the tochpad before clicking, just move to the button you wanna click on and directly press down when you reached it (hopefully you're over the area on the touchpad that can be pressed down )
I don't see a problem with the fans, the only time they are really loud when you turn the device on - during the bios tests.
the brightness thing resetting I have sometimes too, but mostly only when connecting or disconnecting the power, otherwise they stay mostly put. I think I disabled the brighness management in some gnome config utilty.