I love MT. It's definitely useful in a street fight, especially if you train for Vale Tudo style Muay Thai. Get your muscle memory jogging to stomp and soccer kick a**holes when you get them on the ground.
Might be barbaric, but so is streetfighting.
I train completely for self defense. If somebody wants to hurt me or someone I care about, I want them to pay. Don't forget to use the "ambience" of wherever you're at. Like someone else said in this post, always look for the worst. Most buttholes that get into streetfights are showing off for friends. So focus on finishing your opponent as quickly as possible (preferably with a bar stool or something) and keep it on your feet in case his buddies are feeling froggy. If it does go to the ground, get up ASAP.
Don Frye's Mustache > Kimbo's Beard