Not an opinion on the RAT 7, but I just wanted to second whoever mentioned the Deathadder. It's a very sound mouse, built for large hands. It has a trustworthy sensor and it's by far and away Razer's best product both in quality control and in actual usefulness. The price is right on it, so I would second it. Another mouse (that costs about the same as a Deathadder) that has a very good sensor and is a large ergonomic mouse is the Zowie EC1 eVo. Personally I really like the sensor in the Zowie 9club, 9977club.com (it's the same as the sensor in my current mouse, the AM) in that it has no accel and no prediction. The sensor in the Deathadder is also free of those two problems making these two mice very strong choices for someone who wants a large ergonomic mouse. If you want a large ambidextrous mouse with the same quality sensor as the two aforementioned, then you're pretty much SOL
. There are plenty of large ambidextrous mice (such as the Steelseries Sensei) but they all have issues with acceleration or prediction or both in the sensor.