Hey Edwin,
I'm with Bill, my vote would be to use the Calton with some extra stuffing. Check it, and don't worry about it. Do the latches lock? If not, tape them. As John says, insurance is your pal. I've got an all risk policy with a lot of gear on it and I never think twice about paying that premium.
Gig bag makes me nervous too. Some guys do it all the time (Haslip!) but it is at the airline's whim and if they say no you're just screwed.
Shipping case as checked bag can work, except TSA might want to open it ... and the airline will likely charge oversize fees.
UPS or FedEx option is good too but needs a signature required destination, packing, unpacking, and repacking to ship back, insurance again...
You've gotta bring it though!! Have a good trip and gig!
Jimmy J