Ex Grunt, operating at 14000' for sustained periods would not be an issue for most fit pilots. The effect of altitude is logarythmic, though, and you have seconds at 40k.
The discussion about peak cabin altitudes is futile and utterly misleading, and quite likely what the manufacturers wanted for certification. Get a big enough hole and your cabin altitude will match the actual altitude in moments, and that does not necessarily mean an irrecoverable structural failure - have a door blow out and you'll have a very fast and complete decompression, but there's a pretty good chance of dealing with it.