In the 1990's the MAEs and Gigaswitches would give us an unscheduled failure of a major exchange point on a regular basis, which let us demostrate our disaster recovery capabilities. With the improved reliability, i.e. the PAIXes haven't had a catastrophic failure, we haven't had as many opportunities to demonstrate how well we can handle a disaster at those locations.
Without creating an actual disaster, what if all the providers turned off their BGP sessions with other providers at a PAIX (or Equinix or LINX or where ever), both through the shared switch and private point-to-point links, for an hour. More than likely no one would notice, but then we would have some hard data. Individually providers have tested parts of their own network, but I haven't heard of any coordinated efforts to test recovery across all the service providers in a particular location.
This was more or less done in Sweden two weeks ago. In Stockholm there are two sites located in Government own locations. We migrated one of these sites to a new location, and then shut down "one of the halves" for around 8 hours. Best regards, - kurtis -