Leeneia, the case in question would fit into an overhead but wouldn't allow for anything else to be put in front OR on top. Trust me - I have one. And I am a short person. And I have travelled with it. And as they are entirely designed and built for travelling (on airlines as well as other forms of transport) and as the case is built to go with the guitar, believe me they are made strongly and well. I wouldn't want to put one in the hold, but then I wouldn't want to put any instrument in the hold if there was a choice, no matter how strong the case. I've done it - I have tales to tell and insurance claims to prove them.
If you are wanting to know more about Voyage Air guitars (and I believe Deb Cowan's is one of them) then google them - there are videos on line to demonstrate them in use as well as how to pack them.