Hi Steve,
I agree, the 10uF is overkill and mostly experimental. So I get the feeling from what I do understand about the A/D function is that once the sample is made and converted, any more sampleus time is just that, non producing hang time.
Then all I really need to consider is the calculated time it will take to allow the conversion to complete based on the circuit's impedance and your cool PIC multi calculator and go on with life.
Thanks for sharing that tool, by the way!