I hope this info helps (esp. for Mark Sabourin).  Over the past several 
months, I've become very familiar with the effects of distributor tinkering on 
my 71 bus...

When I got my bus, it had the 009 in it, and didn't run too bad except for a 
pronounced "flat spot" going from idle to higher RPM's.  At first, I thought 
this problem was caused by carburetion, so I began tinkering with the 1971 
34PICT-3 carb (bad idea).  I never could get rid of the flat spot.

Around this same time I ran across some articles describing this problem, and 
they mentioned the 009 distributor's lack of vacuum advance (it's centrifugal 
ONLY) as being the main source of the flat spot/hesitation.  I decided to put 
the stock distributor back on (obtained at a junkyard), which is vac adv and 
centrifugal.

It turns out the 71 is probably the worst bus to put the 009 on, due to the 
34PICT-3 carb and it's underjetting and measly accel pump response at the low 
end.  a 3/93 DBHVW's article suggests you can drill out the carb, but the real 
culprit is not getting enough quick spark advance (provided by the vac advance 
distributor).

I don't know which bus you have, but this may help you out with your decision 
on which distributor to use.  The 009's are readily available, anywhere from 
VW shops to mail order (including JC Whitney).  But I like the idea of having 
both vacuum and centrifugal advance - a good compromise.

Good luck