My personal advice is just to remember what they are really "for". They most likely won't help to actually train, unless your little one just refuses to pee when it's on. But in our house, they were good to aleviate some of the stress in the people when training.
The best way to train is to watch like a hawk. But even i know that's not 100% possible all the time. So the belly bands can help in a pinch. I just didn't depend on them. Also, when accidents do occur some people in our house (my hubby) get upset and it stresses us all out. So used with good purpose, it can avoid some of the stress of accidents.
Good Luck!!