The 80C thermostat is a standard performance tweak for the I4.  The folks
at techtonics normally suggest a matching radiator temp sensor installed at
the same time so the rad fan kicks in earlier.  My "pimped" 84 autocross
Scirocco is set up this way.  It is definitely designed to keep things a
little cooler in hot weather, especially with higher compression engines
where knock (and retarded timing) will reduce power.

I wouldn't install this in the vanagon...especially if it is used in the
winter.  With the 17 litres of coolant in there, and a huge rad, a properly
maintained system will have more than enough cooling capacity.  In any
case, glad to hear you're back in shape.