I am not aware of a model PSR-E430. Do you mean the PSR-E433? If that's so, then the sustain pedal can be programmed to act either as a sustain pedal, like the damper pedal of a piano, or it can be used -- I believe -- to hold an arpeggio pattern (I haven't checked this feature in a while, and I only use my pedal as a sustain/damper pedal).
On the PSR-E433 (as well as the later models E443, E453, and E463), if you have split the keyboard by using a split voice, the sustain/damper function only works for the right-hand side of the keyboard.
In any case, I agree that having a sustain pedal is a worthwhile purchase. Like was said above, even a new one is not that expensive, and it can greatly enhance your playing. Not just for piano sounds, but also for any sound where you want to make a nice, lush transition from one passage to another. It works great for strings, choir, and other "pad" type sounds.