Well this has certainly turned out to be a popular thread... 30 (yes, thirty) posts from PNL must surely be a record for one thread
I think we're now very clear on PNL's viewpoint, and FIAT's official word (and how it translates into practice - thank you T14086

)
I have just one question: Of the Stilo springs that HAVE snapped, was corrosion likely to have been a factor, or does it seem like a 'random' break in 'clean' steel?
FIAT are dismissing this as corrosion-related. I have certainly heard of (and seen) springs that snap on other cars for no apparent reason. The break is often part-way up the spring (e.g as PNL said, two coils up from the base) and therefore it seems unlikely to result from salt-rich buildup around the spring perch (strut plate, whatever you call it).
I am very clear on the purpose of the cup-shaped additions...
I have never seen thick steel rust through - it's hard to imagine a spring rusting through... On the other hand I can understand why the spring support might rust through or be weakened enough to bend, but this doesn't seem to be a common problem (well, only reported once).
My question is very important to Stilo owners like me, in NZ, where our springs and struts still look like new (well mine do anyway)... low mileage, no salt on the roads (though it rains a lot), original paint on suspension parts still looking good. It would be nice to know whether the springs are likely to break with no warning, or whether, with no corrosion taking place, they will last normally.
We have, of course, no mechanism for a recall to take place (the thought of a drive to the dealer 140km away and a 'courtesy car' for the three-hour trip home+back to the dealer seems a good joke to me...)
-Alex