Problem is, most "balancer machine techs" don't do it right. How can you tell? If you see them poke the tire on the machine, spin it up, add some weights, maybe spin check it again and take it off the machine and mount it. Chances that it's balanced well are slim to none. It's tough to get an excellent radial/axial runout balance with just one time weight addition.
If the tech spins, adds, spin checks, moves weight, spin checks, and maybe a third or fourth time, you know he/she's taken the time to get the best balance possible. Sure, takes a few extra minutes, but that's the only way to be sure.
Better yet is the load balancers that work off your suspension. But I know that most tire techs get paid squat so they don't care as long as the computer says it's good enough.
2010 2SS/RS Auto, Sunroof, Engine Cover. Transformer Edition package.
2013 ZL1 ragtop #5478. 1 of 54 CRT M6 'verts.