Hi there,

Yeah I agree competitive research is good, and for certain quick and dirty analysis I'll just use Spy Fu or SEM Rush, but in launching a site, critical product line, etc. there are definitely advantages to seeing how a keyword set reacts to YOUR SITE and YOUR offering. Unless you're an affiliate you'll have a unique value proposition, and even if you are an affiliate you should be offering some means of differentiation from your competitors, so getting proprietary data to work off of before committing a lot of resources has significant merit, in my book.

Tom