That's what I'm after really; I had a terrible injury last year which stopped me from running for a good few months (a tendon on my left foot had some really bad injury so walking was painful at the time!). After I recovered, I search for anything that has some good cushioning on them.
I'm not sure though if this brand is good with balance; I'm trying to find shoes that will support me whilst I'm running at full speed (I had an injury where I sprained (and almost twist my foot) because I stepped on a small uneven stone! Was a terrifying moment for me really since I was limping when I went back home)
The sales guy showed me this other Adidas brand where he demonstrated that even a steel ball will bounce if it hits the shoe's foundation! Not too sure if this is good for balance as well.
If that's all your after I'd just go for the ones I recommended, in all honesty any spring mechanism is usually not much more than a gimmeck.
As for the steel ball thing yeah the spring may work with a steel ball but unless you way 4 pounds or less then you won't feel any benefits of that. Like I said it's a gimmeck.