A most excellent analysis, Chun-Tzu, and I look forward to your assessment, CRGreatHouse.
Count me as on of the increasingly many INTPs. The test result was ISTP (Mechanic), but after reading the description of the difference between S and N, I felt closer to N. Previous tests (even different tests I found on the Internet) listed me as INTJ, though this particular test had a stronger bent towards P than J. So, certainly somewhere between Mechanic (my Dad was an actual mechanic) and Thinker seems applicable.
The lack of "Doers" seems somewhat intriguing. In my team meeting, where we did this, made up of all computer professionals, we had no "Doers", and no "Artists" and no "Performers". We had one "Visionary", and one "Executive". I was the only "Mechanic", listing myself in that way, at that time. More than half of the group was "Duty Fulfillers", and there were a fair number of INTJs (probably statistically more than what you'd find in the general population).
My team did this amongst ourselves a number of years ago (different team, same company). There were 5-6 of us, and every one of us was an INTJ. The guy who asked us to do it had done it at his church, and among 300 people, he and one other guy were the INTJs. So, for the entire team to be INTJ, was pretty intriguing. And certainly, in our group, "ISTJ" - the Duty Fulfiller is certainly not far from that mark, anyway.
Admittedly, this test may not be perfect, and the true, larger test would yield more accurate results. As Chun-Tzu points out, it defaults to one or the other if the result is 50/50. Seems like having an uneven number of questions here would have resolved that issue, at least slightly. There are several other tests out there. Just google on "Myers-Briggs".
I wonder if this breakdown might finally help answer the age-old question - "Why don't more women game?"