I'm not against balancing bikes but I don't think training wheels do any damage either and I don't see why it should be one or the other. The great advantage of training wheels imo is that they allow the child to cycle together with slightly older kids and cover some distance, set the training wheels a little bit of the ground and she can always practice balancing in a straight line by not letting the training wheels touch the ground.

Getting form training wheels to fully self balancing is usually done in one afternoon, if the kid is ready. I don't know about things like the balance buddy. Almost everybody here uses a scarf or a towel and put around the chest, under the arms and hold it loose but with a firm grip and jog next to the bike. Balancing is the child's job, the adult's job is to prevent the kid from falling so the learning process isn't interrupted and motivation disappears.