Got mine now and must say: It's ok.
The Savu is much better for me as it has both higher max tracking speeds and better cursor precision. The Lua has some prediction as far as I can tell (I don't mind it though) but also seems to have very slight amounts of jitter. Not as bad as the Abyssus or the DA sometimes have (at least 3G or 3.5G), but noticable on slow movements. Between my three ambidextrous mice (Abyssus, Kana, Lua) it is the one I would go for. It has lower max tracking rates than Abyssus, but the glide is better (Roccat have awesome mouse feet!) and the cursor precision on Abyssus is just horrible. Kana has the horrble side buttons. Downside to the Lua, as someone else already mentioned, is how narrow it is at the front. It's ok, but not really comfortable.
Funny enough: Contrary to the Savu the Lua works better on the Puretrak Talent than on the Steelseries NP+. My testing results are below, all at 1000 Hz.
500 dpi, Puretrak Talent
1000 dpi, Puretrak Talent
500 dpi, Steelseries NP+
1000 dpi, Steelseries NP+
So mine seems to work fine on both 500 dpi and 1000 dpi. I think I would use it on 1000 dpi from how the cursor feels.Edited by Ino. - 5/27/13 at 3:25pm