> Now with the package stuff the (require 'slime-autoloads) line is
> unnecessary.  But additionally somebody claimed that it's idiomatic to
> call slime-setup automatically in slime-autoloads.
>
> I quite like to see the explicit call to slime-setup in my .emacs, but
> others might not.

In this case I would not autoload that (though it wouldn't be terrible to do so). It's not idiomatic for minor modes to turn themselves on as an autoload.