The huge deflation in labor made it possible to keep these rates low without inflation

from my perspective you have the cause and effect backwards.  Greenspan didn't keep rates low, they had to be low due to economic factors in the global economy.

1.  markets opeing globally unleashed a huge labor pool of underutilized labor.
   
2. A.  this put big downward pressure on labor costs.  and,
   

    B.  it opened up great opportunities for growth, as this labor was put to use making less expensive products.  Capital was needed to meld with the labor to create jobs.

3.  I'd have to check economic history, but I think as long as monetary policy was well thought out, real interest rates have been between 2--3%.  So add that on top of 0--2% inflation, you get 2--5% interest rates.
   
4.  so how could this not happen (sans horrible central banking policies).  underutilized labor, lower prices, negligible inflation, growing demand, supply side begging to work.  of course cost of captial is going to be naturally low, and working in concert with the other factors,,,,voila.

I'm not trying to argue Greenspan was perfect.  I'm just saying he is not a fundamental factor that has led to low inflation, strong economic growth, and low cost of capital.  He should get credit for being an adequate central banker, implementing policies consistent with economic principles of his time.  Obviously the Fed messed it up during the great depression (but I guess some of this knowledge was not available then.)

actually I think the boom would be far stonger in the euity markets without the terror issues in the MidEast.  There is a large risk premium on financial assets, imho, due to this factor.  these factors will make markets grow steadily since the risk premium is already there.  but if things ease in the mideast (and I doubt it), but if they do.  watch out, these equity markets will explode.

as to Japan, I think it's a prelude to the future.  the next 5 years demographically will be OK for them, so their markets will be OK.  but then it comes back, and begins to hit the western world as well.  I don't know if we have answers for this one yet.  (I know this is not accepted economic thinking, btw.)