Gosh - I'm afraid the OP has put me off purchasing ear canal type headphones
I was worried about the possibility of ear drum damage as well as the collars detaching and remaining stuck in the ear canal. I'm willing to put up with the discomfort of "cans" to avoid these possibilities.
I started out with the Bose QC2 which sadly disintegrated after a few years usage. I replace these with the QC3 (very nice sound and size) and I've very recently added a pair of Sennheiser PXC450s.
I haven't yet had the chance to "prove" the PXC450s on a flight, but should be doing so in a couple of weeks. The PXC450s are
HUGE - even larger than the Bose QC2s. They also require a lot of power to drive them - I was forced to to turn the volume of my Ipod Touch to near maximum - and even then the sound was rather weak. They only reach their true potential when driven by a headphone amp. I got very good results from a pocket CMOY amp and acceptable results from a small el-cheap FiiO E5 headphone amp.
The FiiO E5 pocket amp is actually a pretty neat bit of equipment for the price range. It is small and non obtrusive and certainly enhances the listening experience. I have to give it two thumbs up ^^