Only if you are not using it to PLAY...

(or were you simply referring to the 'middle finger' )

Quick question. Let's say you HAVE to play a chord AND hit a fill button at the same time. Which one do you decide is going to be late (or early)..?

The foot is incredibly precise. Look at how accurately it is used for sustain (well, OK, in your case, not.. But in MOST people's case it is! ). What makes you think it can't be that accurate for a fill?