EC2-a would be a smaller version of the DA, if you liked that style you would probably like it more than G303. G303 is more like a fingertip/plam hybrid grip mouse... at least that's how I used it with 19cm hands
I had a EC2-a (which I ended up returning) and just got my ZA11 yesterday. The ZA11 fits in my hand much nicer, I find it easier to hold/pick-up than EC2-a. I have 19cm hands. As far as using it for claw... I dunno, it's made for palm grip. Take look at Fk1 instead maybe.
Why do you want a Zowie? You also play League, Dawn of War(RTS?) and PoE, all games where you click a lot. Most people can't seem to handle Zowie clicks for those games. The EC1-a will have better clicks than the FK1, my FK1 clicks are really stiff, but my EC2-a were great.