We have a flutter, pep, and some other travel device. As long as they are healthy, I personally think it is ok. I agree, they should get a vacation too, unless they are sick, having lung issues, or coughing up stuff and really can't afford to miss the vest. Plus, it has been our experience that when we change to something new, that we haven't used before, it sometimes works a little better than the vest, at least for a few days before it stops being as effective as the vest. The key is making sure they are doing it correctly, which is not always as easy to determine as it is with the vest. Plus, the cold tends to make Nathan have a dryer cough and less productive and the vest doesn't help make a difference, its hard to loosen stuff that is all dried up. Again, as long as they are healthy, I would probably give them a break and a chance at a real vacation and leave it at home, making sure that there is an understanding that this is for vacation time only.
Have fun on your vacation!