I never  had  a  hot start problem with any of my VW starters.  I did
put a remote relay in most just to get the heavy gauge wire out of my
way.   hot air has to be getting to the solenoid some how or air is not
flowing over it to keep it cooled  from the engine.  on water boxers
this is a big problem for people that switch out starters on automatics
because the starter usually sits right below the exhaust headers and
they dont go through the PITA problem of putting the heat shield back
on.
jimt