X-Plane:
* Has the most accurate flight model -- so accurate that some manufacturers use X-Plane to flight-test models not yet produced.
* Can be FAA-certified for instrument training
* Can be networked among multiple machines to power multi-monitor cockpit setups
* Can be extended via plugins, of which a wide variety are available
* Has an extremely active developer community-- plugins, aircraft, scenery
* Can be used to fly online with VATSIM (US) and IVAO (Europe) - where there is often live ATC and where griefers are kickbanned liberally.
* Has an awesome developer blog, talking about 3d graphics implementations at a very low level: http://xplanescenery.blogspot.com/
* Has Austin Meyer (owner/lead dev), who is a colorful personality, and blogs often about aviation and other miscellany: http://www.x-plane.com/pg_PIREPS.html
* Is available for iPhone and iPad
* Can use your iPhone or iPad as a joystick and to display instruments tied to the sim on your computer
Also, I know "FAA certification" is an oft-touted feature of XP, but it's not certified as a simulator, only as a "flight training device" and at the level it's certified the bar is pretty low.
If you're looking to get sim time for an instrument rating, it's helpful but it's not as impressive as it sounds. XP's certification level is more about, "if the joystick is unplugged, pause the sim" than accurate aerodynamic modeling or flight model completeness.
http://www.flypfc.com/index.php?i_id=29
http://www.fidelityflight.com/newmotion.htm
http://rkaplan.hypermart.net/simulator.html
Though you are right in that these are still only currently certified as FTDs, you can still fulfill, for instance, up to 50 hours of seat time for your ATP certificate. See FAR 61.159(a)(3)(i)
And while it's a great program, and other than the nicely crafted missions in FSX... X-Plane beats it hands down. I haven't looked back, especially since I can run it flawlessly on Linux.
One thing a pilot is never allowed to do, is give up (no matter what); and neither should you if caught in a survival scenario.
If this is a real concern for you, check out something like the AOPA Pinch Hitter's Course, which can teach someone to land an airplane during an emergency with only minimal flight training. See http://www.avweb.com/news/safety/183024-1.html
If your question is more along the lines of "does a simulator make an acceptable substitute for an aircraft?", the answer must be no. Simulators are really only useful as a supplement to actual flight experience and training.
One of the things I remember when first starting was the sheer amount of "stuff" going on in a plane that I had to worry about. For example taking off you've got maintaining the center line/winds (aileron position) checking engine instruments, radio calls, speed, and traffic. Having seen some of these components virtually may alleviate some of that head spinning that goes on. You'd know what flaps are, and when they are usually used, you'd know what a flare is (and that you didn't need 37 pieces of it).
You would also have exposure to various IFR procedures commonly used in the real world, most useful being ILS, which can line up your aircraft with the runway and put you on the correct glide slope, and even land the plane.
I would also suspect you would have a bit of a confidence boost (that is if you're optimistic), something like "I've put a 737-700 on the blocks hundreds of times in MSFS/x plane - how hard can it be?"
Of course this is all wild speculation, and the odds of an "Airplane" scenario are pretty small.
He claims that any non-actual-pilot will be unable to land a commercial airliner in a full-motion simulator, given the controls mid-cruise. Whoever loses the bet gets to pay for the simulation time (ouch!).
If I had the money, I would take his challenge in a heart beat! I am open to accepting funding ;)
With enough time in a realistic aerodynamic model + cockpit setup, on a modern aircraft (that has a high degree of automation already), in favorable weather conditions and a long // wide enough runway I think it's probable you could fly the bird to a safe landing.