That said: Some time ago, I asked if it would be possible to have
NO compile_dir at all (and recompile the templates every time).
IIRC the answer was "yes, that's possible", however I have no idea
how to do that.

There's a config parameter to do it. Can't remember which ones, but
It is possible to do with smarty.

I tried googling this, but didn't find an answer. Would be nice if you
can find it out ;-)

I suspect it's : ?