Some observations so far:
NTPs are indeed being typed correctly (or at least as the type they believe themselves to be) more often than not, as teslashock said. Those with Ne dom or aux (NPs) also seem to select the Ne statement when it's an option. So, the Ti and Ne statements seem to be getting responses from strong Ti and Ne users. A couple of self-typed INTPs did prefer the Ni statement initially though.
Fi-doms don't always seem to be resonating with the "life based on empathy..." statement. I count six self-professed Fi-dom posters in this thread and three selected that statement. Two preferred the Ti "I want things to make sense..." statement and one preferred the Ni statement.
So far, Ni-doms have selected the Ni option half the time and the Ti option the other half.
There has only been one SJ poster in this thread (TheChosenOne), so it's hard to say if the Si statement ("People can trust and count on me...") rings most true for them. TheChosenOne's ISTP result means the Ti statement was selected over the Si one.
And, interestingly, the only people who seemed a problem with the introvert/extravert question were ISFPs (wolfy and Walking Tourist). I suppose SPs tend to like to engage themselves in a busy, active environment regardless of I/E. Might it be better to mention engaging with many people, specifically?
Perhaps those of you who aren't getting your type can suggest a statement that accurately captures your dominant function(s) for you. What does Fi, Ni, etc. mean to those of you who use it most?