Yes, you can do some cool stuff with that and you can have osc3->osc2-osc1 in the mod matrix as well. Or even osc3 to osc1 and 2 separately. Or Osc1 and/or 2 feeding back on it's own operators
Make sure to change the modulation rate in the settings tab of the central window, in case you haven't already. Higher CPU, but better sound, unless you like it grungy!