Hi,
I do like this training device, because flying with it doesn't break the
helicopter.  I would learn to maintain the stability and I would move the
helicopter without have experience like me. I think the other device it is ok
to learn hoovering ( after the radio is setted to avoid the spinnning etc.) and 
only when the pilot has some experience, because it's enough just a one wrong
command that the model go to ground imho.