The G3 is a bust. I tried it and the screen is pretty much not even noticeable and LG introduced a lot of bloat and lag in the animations. The G2 ran better in my experience with it.
I am more than happy with my rooted and rom'd "regular" S5.
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G3 have oversaturated, oversharped (halo effect) screen with bad viewing angles, bad contrast and distorsion colors