Seems risky at a company full of tech nerds. If they see you doing data mining to figure out who is likely to leave, and scratching their itches, what is to stop otherwise happy employees from "life hacking" so that it will look like they are unhappy and look like more money/vacation/benefits/advancement would help retain them?

How sweet would that be? Figure out how to look right on the report, and you've implicitely threatened to leave and shaken them down for more, without having to make any such threats explicit.