[Elecraft] DSP - 4 questions

[tlogan7@cox.net]

Hello fellow Elecrafters - 
There is a chance this message may show up twice - if so I apologize. Anyway, I read the product and technical artical on the DSP and it is above my head. Here is what I would like to know:

1 - How much noise will I notice if I add the DSP unit?
2 - Cab the DSP unit be disengaged at will so any DSP noise is not constantly present?
3 - If I am mainly a cw op, is the KAF2 a better choice than the DSP unit?
4 - What is the answer regarding trade-ins/returns/credit for new unbuilt KAF2's that were purchased prior to knowing about the DSP unit?

Thanks for any help on the above.
73/Tim