I've flown w/ the 14" in economy and didn't have a problem. You do have to be alert in case the passenger in the seat in front of you reclines suddenly (snatched the lid of an x60 out of the way just barely fast enough once), but it should be OK.

Now that I'm thinking about it I didn't have a problem w/ the 15" Intel either, and the dimensions are pretty similar. I'm pretty slim and short though; I don't feel like a T-Rex typing.