I've been messing with placing the squelch on 0 or placing the squelch on 2-3. I don't notice any difference. Is there any performance difference between having an open squelch or a "tight" squelch when scanning one or more digital systems?
Generally not if only listening to systems that are monitoring control channels. But if you also monitor conventional stuff, the squelch will always open and stop on noise.
Setting to zero can also potentially slow scan speed.