I used to use it, from about 18-22 years old. I still use it for one of my 3 treatments a day usually, but my primary method of airway clearance now is the vest (I had used the vest prior to switching to the IPV, but I switched back and upgraded models).
This is basically a big nebulizer that "pulses" and sends saline and air into the lungs with each pulse. Like the vest, you can control both how hard and how fast the machine pulses. Personally, I prefer higher pressure and slower frequency, but it might be different for a younger child. Like the vest, I go in 5 minute cycles and stop to huff after each one. The machine is very effective, especially when used with HTS instead of normal saline, although that gets expensive since the neb requires quite a bit of saline.
I have known a lot of doctors who think the IPV is more effective than the vest. Personally I think it boils down to the individual. People with a history of hemo or lung collapse are sometimes warned against the IPV, because it can irritate the airways and it works by a sort of internal percussion by inflating the lung. There's a good chance Cheyenne will like it. I certainly did - and it's more comfortable than the vest. The downside is that it's kind of a pain upkeep qise - lots of neb parts and tubing and it tends to spray saline all over. Fun fun.
Good luck!