Is it possible/reasonable to wire motors to the 74HC595 as a polar switch? I have been using relays to do this, but I wasn't sure if I could control even more motors with the IC?
No, the 74HC595 cannot supply the currents necessary to power motors. You will destroy the 74HC595.
-- The Flexible MIDI Shield: MIDI IN/OUT, stacking headers, your choice of I/O pins
That's what I thought :/ Thanks!