One of the guys I do trackdays with, has a bt014 front and corsa 3 rear.
Some people will say, oooowwww dont run different brands, but ive never had a problem with it.
On the road it make less difference than if it was on track.
I wouldn't run different front/rear tires. With the rear being more sticky it could very easily push out the front. Not only that, if you get caught in the rain w/ different tread patterns....not a good day!