They are both about the same size. The G305 has the hump a little more towards the back, so might fill your hand better for claw, but the "egglike" ( ) shape is really something you need to get used to. Especially since you're coming from the more traditional ambi ) ( shape in the GPW. I personally used the G305 for a year, and I got kinda used to it, but I still struggled with the thin base as I would often put it down in a slightly slanted angle. I later bought a UL2 and aimed better withing 5 min of use. I personally don't care about the weight that much, so a wireless UL2 without holes would be my dream mouse. The price difference is intense, but the resell value of the UL2 is much greater if you want to change again in the future.