If an 'experiment' trying to compare a C and an Ada team resulted
in the C team creating a new CASM (C Ada Subset Macro) language
that was better than either C or Ada, then we'd surely like to
hear about it.  If it was better than C but worse than Ada (or
the opposite) then it should prehaps replace whichever it beat,
and if all three were in a dead heat then it's evidence of 'no
difference' - at least for that application domain and set of
programmers.
  Clearly such an experiment, especially with a 'Western Electric
effect', and across multiple apps and programmer sets, is not
something to be done definitively by a few folks, even at a large
company.  Even non-experimental collection and analysis of data on
past projects is a big job.  But if we're looking at a likely
DOD-wide, or nationwide, or world-wide, benefit on the order of
$10**8 or 9, then it's well worth a *substantial* investment.