CD4053 to swap transistors?

[tss]

I am trying to put together a simple setup based around the article from geofex. I want to basically control which transistor is connected at a certain stage in a circuit. I thought to switch the base + emitter from each transistor - does that make any sense or another combination should be chosen? Another question is about the actual schematic on geofex, the bias voltage for the CD4053 is fet through a 510K resistor and I am wondering why not a higher value?