Hi Paul,
You can't run logic written in one Model in anther Model because most probably syntax will be incorrect. So, RUNLOGIC implements the second case. In some instances you really can achieve same result just by renaming Model in the DMP, but you can't pass parameters used in one Model to another Model. And that's what RUNLOGIC allows to resolve.
Please let me know if you have additional concerns.
Regards,
Gersh