Which foot you use to brake has nothing to do with how well you drive, or how smoothly. Many of the best road racing drivers in the world use left foot braking.
That's a matter of opinion. It's a technique that needs to be mastered. Most left brake enthusiasts would say they have mastered the technique, when you should really be asking the passengers. From my experience with a left braking ambulance driver, he would definitely say he has mastered it. Though 100% of his passengers (and patients) beg him to stop giving them whiplash.
If you're referring to a race driver with no passengers, fine do what you want. If you're talking about doing this on the road with passengers and in traffic, then stop kidding yourself.