You MAY have a painless experience. Or you MAY have a traumatic experience. It all depends on the officer and how much he likes or dislikes you - which is one of the most terrible weaknesses of this program.
You can read about my experience here. Like you, I honestly said that I was unemployed, which apparently was a red flag for the officer who interviewed me and then proceeded to verbally abuse and threaten me.
http://www.flyertalk.com/forum/pract...bal-entry.html
After this experience I was told by everyone who I talked to that I was suspicious, wasn't telling the whole story etc. - this simply goes to show how our society tends to slavishly believes in the decisions rendered by "authority figures" since most law abiding citizens have never been mistreated by people in authority and tend to disbelieve such accusations (until it happens to them and they are surprised).
Why do I feel that I can say this credibly? Because after complaining to people I know in DC, a few months later I was approved for Global Entry and apologized to profusely by upper management for my treatment.
So what changed between then and now? Absolutely nothing. Always had a spotless background. I just simply received an officer having a bad day - or something.
The lesson learned: Do not automatically expect to be treated professionally or fairly by the front line officer you deal with. Most people are treated fairly, but not all. Do not be taken by surprise as I was. It probably won't happen, but with your background it could.
If you feel you are being mistreated during an interview, be prepared to speak to a supervisor and go up the chain of command and demand that the people who are working for you treat you in a respectful manner. Yes most officers are just doing their job and are good people, etc. etc. But my sense is that many people simply accept mistreatment or don't believe it happens.