Two more important points about left foot braking. This is not a good idea if you're driving on a motorway. Period. You should never rest your foot on the brake pedal. If you don't rest your foot on the brake pedal, why not use your gas foot. That's why they make them that way.

Point the first: Left foot braking, leaving your parking brake on, or any other constant braking can cause the brakes to warp. Warped brakes will make your driving experience less positive because they will make your car vibrate and reduce the effectiveness of your brakes. More importantly and more funny: Left foot braking can light your brakes on fire! Why, killermonkeys, you say? Well, brakes are friction devices, and they get hot as hades when you use them. If you use them all the time you will get them so hot that they will start burning the pads (which is the brake smell). If you get them really hot they will burn everything else. If you get them really really hot and you're having a bad day you can get a spark (your brake pad is carbon metallic, your brake is steel, it's not that hard). They will ignite, and they'll probably burn any oil, grease, and other hydrocarbons they can find, including and not limited to your car. But you'd have to be pretty stupid for the car to burn to the ground, but we're not going to exclude this possibility.

Point the second: To confuse you left footed brakers, left footed braking is a common racing technique in off-road rallies. Why? Because they have turbos running 27psi of boost, and they have lots of turbo lag, and basically, if they take the foot off the gas, it will take a long time for that boost to build up. So, to fix that, and to take advantage of the fact that they can slide around in the dirt, they brake while accelerating. You, however, are not on the dirt, you're on a highway. And unless you're incredibly cool, you don't have 27psi of boost. Moral: the foot that does the braking is the same foot that does the gasing except in heel and toe.