Murray. You're absolutely right. Airport security and regulations have changed dramatically in the last few years. I would NEVER "brazen it out" (as I did for many years) these days.
Sadly, you simply can't trust airport personell to respect your property...and it seems that a "FRAGILE" sticker just makes them meaner.
Can you imagine for one minute that a handler who DELIBERATELY smashed your instrument would even be disciplined, let alone lose their job? Not a chance. I'm afraid the only "sure" way, is to "leave the Martin at home" and have a cheap guitar to travel with. Sad.
Or get a Calton case.