A buddy of mine and myself have played with balance dots in the past using his tire machine in his shop for exactly all the reasons you listed. Since this is what he does for a living, he figured he better do his homework. We saw very little to no difference in balance when shifting the dot around. And we were using the balancer in the micro balance mode, which will pick up down to a few grams of weight.
5 grams = 0.17 ounces. Typical stick on weights come in 1/4oz segments.
JMO, but we discounted the whole thing after that little experience. Others may have a different opinion.