Good summary TSP
Its good to hear some rational thought process being applied to a situation that never should have occurred. Dual redundancy issues have been with us for many years and it seems that whilst the Reliability Block Diagrams for the system show a good mathematical model, the changes of technology always manage to throw in one or two technical spanners. This will always be the case, its the recovery process (as TSP said) that should be the centre of development.
Thales, like everyone else will try to use as simple as possible components, based on the principle that 'complexity' breeds further 'complexity' and simplicity breeds good understanding usually. The down side is that simplicity is usually commensurate with mass production and this will therefore introduce the probability factor that there will be one bad egg out there just waiting to rear its ugly head.
As a point of view from working extensively with Thales over the years; my criticism with their system is that its designed by engineers and is really best suited to be operated by engineers, which is of course completely wrong. Even Thales admit their 'user' input into the ergonomics and friendliness of usage was extremely low, especially with the EuroCat 2000E systems and its derivatives.
Raytheon certainly beat Thales in this respect, but there are issues here too. However that is best placed in another thread. As far as the Thales IAA system is concerned, there were many flaws with the first delivery and without the European backing for funds this system would never have been introduced. But it is what it is and they have to make the most of it - question is, will they learn from the experience in 10 years time?