I'd vote no to Miz. I think you want to:
Save Miz for a must-win game 5 (if necessary)
Save Miz for game 1 of the Dodgers so he can pitch twice in that series (if necessary)
While Gasser isn't a great match up with the Padres, he has been lights out lately. Since Murphy took him out mid-AB, he has a bit more edge and determination on the mound. I like his focus in this last 3-4 starts.