It's not certain the OP of this thread will read this, as it's a very old thread, but the doctrine of the investigative judgment (IJ) is always relevant to adventists, so I'll share a few thoughts.
First of all, rest assured that all our doctrines soon will be tested with fire, and any doctrines that cannot be fully defended from the bible alone will soon enough prove to be wood, hay or straw.
1 Corinthians 3:12-13.
Of course the official position is that the IJ indeed can be proved by letting the Bible be its own interpreter. In contrast to the traditionalists' stance, there is a minority in our Church who have doubts about various parts of the IJ, and some even reject it altogether.
Disturbingly, there are people who have left the Church because they cannot reconcile our official theology with the Biblical evidence. Some of them go on to reject not only the doctrine of the IJ, but also other vital parts of the adventist faith as a result of this.
I think the problem with the most famous critics of the IJ, is that generally they leave people theologically stranded. They might demonstrate weaknesses in the orthodox position, but they don't provide any new insights that will take adventists further. Instead people are left with the feeling that the advent awakening in the 1840's was based on a delusion, and that Ellen White cannot be trusted. In other words, what are the fruits of their efforts? These critics certainly aren't strengthening the adventist church, quite the opposite.
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Don't get me wrong, I'm not claiming that the orthodox position is infallible. Allow me to draw the attention to another discussion... Before Jesus started his public ministry, the Jews were generally waiting for the arrival of a mighty warrior king that would deliver them from the Roman yoke. Now, were the Jews mistaken when they believed in the coming of the Messiah? Not at all! But were their ideas about the nature of his ministry correct? Well, even the disciples had difficulties when it came to grasping the true nature of his kingdom, right?
I'd like to suggest that the discussion about the IJ is similar to the Jewish controversy about the Messiah. The Jews rightfully waited for the Messiah, but their ideas about the Messiah were far from infallible. In the same way prophecies were fulfilled in 1844, but we have much to learn (and unlearn) about these things, and about Jesus' ministry as our High Priest.