DG.... you are right on... although some of these guys are obsessed with the weight of the car and it has to be as light as possible and that's the only way they can be fast.. but you are right.. corner speed and momentum are huge....
I know people will disagree with me, but I don't care how light a car is , if you cant drive it fast the whole time your still not going to win.
yes the rear motor is lighter, but with a good setup the mid motor is faster because of what you said.. corner speed and momentum.