Sternone
I was warming to some of your points. I appreciate you are also having some fun so I suspect some of your comments are tongue in cheek. However while you are ahead stay there - your last post was just silly.
vanHorck
Well Garmin and Avidyne (the two main players in the certified market) take different views - excuse the pun. Each uses essentially modular systems so more often than not it is one module than fails. For example I have had the DI fail on a G1000, box 1 fail etc. It no different really to when that component fails in your six pack. The whole system is driven by a central processor and I guess in theory this could fail including all its back up modes. In the same way a screen could fail. Garmin overcame thise by enabling the pilot to transfer the PDF to the MDF so you should only be without the key instruments if both displays fail. Avidyne did not employ this approach (at least until their latest upgrade) so if the PDF fails there is no mechanism to paint that information on the MDF. Similarly both initially used a single solid state gyro - if it fails you are without the AI, but then again how many light aircraft have dual AIs.
Things have moved on and Garmin and Avidyne in their latest offerings emplys dual gyros, interchangeable screens and other technology to improve redundancy.
If it should all die on you for certification anything with glass will have a compass, an electrical or vac gyro, and a ASI enough to get you down perhaps with a hand held GPS in your flight bag.