The DuPage FSDO is out of control. They are either the first ones to start a program or they are always just out there doing crazy stuff that other offices don't do. For instance, they are taking away all of the basic operator 135s in the area. Usually this is when you can have 2 management positions combined into 1. They are no longer granting that deviation and they are telling the operators with it to fill the positions or lose the 135. Also, if you happen to let your CFI expire, you can't just go with a DE. You have to reserve a room, fly to DPA, get a DE and the door stays open so any inspector can observe. I know somebody that flew down to central IN to find a DE that could do the ride without all the BS.
As for your CFI ride, call the FSDO and see if they still do the CFI canidate class. As of a year ago they were still doing it. You sign up, go to the FSDO one night and take part in mock instruction situations that are critiqued by at least 3 different inspectors. They say that 90% of the people who attend that class pass their first initial checkride. Maybe when you say, yeah I went to the CFI class and it was wonderful learning experience, then they cut you a break.
I did my ride over 10 years ago and the inspector has retired now. It was foggy that morning and I called and he said why don't you just drive up as I have the whole day scheduled for you. So I did and we had a very long oral exam. He did teach me some things and that is the one good thing with dealing with the feds. They always bring up practical stuff based on accidents that they have investigated. I passed the oral and came back a week or so later to fly. Ended up doing my first 135 check with the same guy. Was nice to have a relationship with him by then.
As for the inspectors, if you get Dennis Caravella, then I am sorry! Dennis Cmunt is a really nice guy, but he is off the wall about a few things. You will learn some things from him, but he will also drive you crazy with some of the BS he comes up with. He is in charge of all the DEs in the area, so he has quite the reputation. Don't believe everything you hear. All the other folks up there are pretty good people (on the ops side).
Take the class and bring as many possible books that you can. Good luck.