a question about quattros and turbos

[Jim Chiodo <jchiodo@gfs.com>]

Looking to replace a 86 5KS with a pre- 92 model (because of
the size) and generally believe in KISS (keep it simple
stupid).  More stuff means more to go wrong.   Due to this I
have not looked at quattros or turbos.  The later also
because it might have been driven hard. 

Even though mechanically capable of most things, (recently
replaced  steering rack on  86), I am not sure I want to
fool around with all wheel drive or a turbo.  Reading
listers enthusiasm, however may have changed my mind.  

What potential problems might I encounter with a quattro or
turbo?  I generally don't get burned buying a used car,
(mostly private), but I have no experience with Qs or Ts. 
Does this greatly increase my chance of getting burned?

What should I be aware of dugin pre purchase inspection? 
Anybody out there care to share first time purchase of a
used turbo or quattro?  Or advice from  long term owners?