And as an avid gamer, including online first-person shooters, I'm saying that having the sensor under the fingertips *still* improves the accuracy and speed in games, in exactly the same way that increasing the DPI does.

Back in the old days, when it was Doom 1 and Quake 1 for online games, I still preferred the Microsoft Dove Bar mouse to the more-popular Logitech mice for precisely that reason: Everything I did was more accurate and faster because the ball was under the fingertips instead of under the heel of my hand. I could do a 180 flip so much better and with so much less hand movement, and yet still had better fine-aim control with more resolution.

You can prove this to yourself with any modern cordless optical mouse with the sensor in the "wrong" place (at the heel of your hand):

First, turn off mouse acceleration for this demonstration. (I have mine off all the time already; I hate the way it feels.)

Start by holding the mouse in its normal position.

Move your hand left and right with a normal kind of at-the-wrist movement, so that the mouse pointer goes back and forth on the screen. Observe the distance that the pointer moves.

Now flip the mouse around 180 degrees, holding it so that the heel of the mouse is at your fingertips, and the buttons are under the heel of your hand.

Now do the same left and right wrist movement you did before. The pointer will be moving backwards and upside down, but it will still work for this demonstration. Notice how the mouse moves so much *farther* on the screen than it did before, in relation to how far you move your hand.