Corner balancing is definitely overkill for for any street car and even most recreational track cars. I can understand why you'd want one though, I'm overly anal like that too
Hopefully you set your tire pressures exactly to whatever spec you plan to run, had the same amount of fuel in your tank you plan to race with, and were sitting in your car. All those things can completely throw a corner balance off. I was actually amazed to see how much even an extra 1-2 psi in one tire can make. Mind me asking what they charged you for the whole package and how long it took? What kind of alignment rack and scales do they use? Did they have the fancy Hunter EagleEye laser rack with scales and tire pressure hoses at each corner to keep the tires at a constant?