The Jack Hyles I knew of was from the mid-80s on. I was saved in 1981 and therefore know little of Jack Hyles or of the IFB world prior to this. It seems to me that he really went off the rails (or perhaps this was when the dirt started coming out?) in the late 1980s with the controversies fueled by the "Sumner Articles" and this crowd really started "circling the wagons" castigating anyone who expressed any criticism towards Hyles or their particular brand of "Fundamentalism."
Seemed to me that at one time, he preached and proclaimed the gospel and that many attest their salvation to his ministry. Hykes-Anderson College has trained many pastors and missionaries and many of them are faithfully serving in the ministry and some are doing so perhaps in spite of the sub-standard training and education they have received? Among these are some I have known and served with personally.
I've noted the same thing. Had some good friends in Japan from the early days of the college. On the other hand, an HAC grad missionary to the military in Germany, who was a good friend, decided to support my ministry so he sent me a 7 page questionnaire. When I saw it I knew the friendship was over. He went off the rails, had moral trouble, had to leave the ministry. His oldest son became an atheist policeman in Florida, then was murdered by a jealous husband. Very sad business.
According to my understanding, Jack Hyles was far more moderate and his stand on the King James was similar to that of John R. Rice. Seems that John of Japan would be able to speak more intelligently of this than I could but John R. Rice reflected the more moderate and sensible wing of the Independent Baptist "Movement" as opposed to his buddy J. Frank Norris but this something of which I would leave you to do your own research - it would make for another interesting topic.
Rice was not KJVO, as you know, though he preached from it and loved it. He studied from the old ASV, and studied the original languages. As long as Hyles teamed up with him, Hyles was not KJVO. In fact, in his book Let's Study the Revelation (1960's), he points out some translation errors in the KJV! In my biography of John R. Rice I have a segment on Norris, and a chapter on Rice's relationship with Hyles, if you're interested. See the bottom of my post.