neeb, thanks for all the information you've provided. I share your frustration with Campy on this issue. An option I'm considering is using the 2011/2012 Campy bolts and threaded inner ring with a Stronglight or TA 48-tooth outer ring. In light of what you've learned about the lip on the Campy outer ring and bolt heads, do you think I would have any luck trying to use the 2011/2012 bolts with a third-party outer ring?
My first thought was that this might work (unlike using the older bolts with the newer outer ring), but on looking more closely I think there might
be at least one potential problem.
Here's the new style campagnolo outer ring bolt hole and matching bolt (for threaded inner rings):
And here's the old style bolt hole (in this case on a TA Nerius ring, although I think the 2009/2010 Campagnolo ones are the same) and the old style (non threaded, 2 piece) bolts:
You can see why the old style bolts don't work with the newer rings - that little step on the outer bolt is obstructed by the 45 degree sloped surface on the newer outer bolt hole. The bolt will go through the hole, but only as far as the step on the bolt.
However, the newer threaded bolt does actually at first appear to go all of the way into the hole on the old style outer ring. For the TA ring at least, when you look closely you do realise that is is not quite as flush with the outer chain ring surface as perhaps it should be, although there's only a fraction of a millimetre in it. This is because the flat recessed ledge on the newer bolt hole is actually slightly deeper in the campy ring than on the TA ring. However, I think this may actually only be because the TA ring is slightly thinner to begin with - unfortunately I don't have an original Campagnolo 2009/10 outer ring handy for comparison. It's difficult to tell if the bolt is protruding slightly further through on the other side or not, if so it is only by a really tiny amount.
However, there is another potential problem - the newer outer ring has a smaller hole for the special bolt underneath the crankarm. The newer bolt for this position is narrower, so I think with an older or 3rd party ring you might need one of the older style crank arm bolts so as not to have a gap. Perhaps this wouldn't matter in practice however, as the ring would still be held in position by the other 4 bolts and firmly sandwiched in place at the crankarm position too, even if there was a gap between the bolt and the hole in terms of their diameters.
So, to summarise.... it might work - especially if you could get hold of an old style 5th (crankarm) bolt & washer (the washers are different too) to use together with the 4 new style threaded bolts. But no guarantees... I guess the safest thing would be not to mix old style and new style inner rings, outer rings and bolt sets.