After comparing the G500 and Mamba 2012/4G for a while, I realized just how important it is for my left thumb to have an area to rest and grip on.
With the standard Naga, that's not possible without pressing on one of those numpad buttons, but the Naga Hex does have a spot in the middle that I could use.
I also thought I'd like the old DPI button position more, but as it turns out, the ones on the Mamba blend in TOO well with the left mouse button, unlike the G500's. While I certainly wouldn't like them behind the mouse wheel either, I also realized how I pretty much stay at 1800 DPI all the time, but may change that since Razer offers an extra button function that, while the button is held, sets the DPI to a custom value. Nifty for precision shots.
Funny how one's initial thoughts change quite suddenly when he really examines how he uses his peripherals...