My wife and I are green card holders as of 10/2/2009. We need to move to India for 2-3 years because of a combination of professional (I need to set up my US employer's engineering office there) and personal (need to take care of my mom after surgery) reasons.

We are planning to file re-entry permits.

As long as we are in India (till 2014 or so), we fully expect to visit the US at least TWO weeks every SIX months due to my employment here. I do want to pursue US citizenship.

Given this, is it necessary I should file an N-470? Is it recommended? Why?