^ On a similar theme to repechage and others...

Obviously, you're planning to swap the pedals anyways - which will quickly help to determine if this is a possibility:

Recently, after completely disassembling, cleaning and repacking a pair of old Suntour Sprint pedals to switch onto my bike, I noticed an irritatingly persistent 'tick-tick-tick' on the drive side. One 'tick' per revolution, always at the same point in the stroke. Turned out that I hadn't torqued down the bolts securing the pedal cages quite enough, that was the source of the sound. Tightened them down, no more 'tick-tick-tick'.

Sorry, I don't know the torque spec on the SR crank...

Just another possibility...if the pedal switch eliminates the problem, it's something to check.

EDIT: I see you swapped them, new post, but maybe still...I dunno.