Last May we were getting ready for a trip to the Grand Canyon. Rather than take a chance (I had heard too many conflicting stories and I kept getting different answers from the airlines), I shipped my Whisperlite and empty bottles ahead. At the end of our trip, I emptied and rinsed out the gas bottles and shipped everything back home.
Then in October I was headed back out to Vegas for a convention (work-related) and then taking several days for a trip to Zion and Bryce. Again, rather than take a chance, I shipped my stove (this time a pocket rocket) and small lantern to the hotel I was staying at in Vegas. When returning, I was flying on Sunday (taking a red-eye back east). Since I wasn't sure if I would be able to find a place to ship stove and lantern back home, I took a chance and stuffed them in my hiking boots, shoved stinky socks on top and placed them in my checked luggage. Of course, I left the cannisters behind. No problems. Everything showed up in Boston, nothing had been searched or touched.
I think it's really hit or miss. If you can, I would suggest shipping questionable items ahead so that you won't run into any problems at the airport.