Grabbing the tmp in the bathroom, even if it doesn't result in a witness, would give the enemies behind me enough time to catch up and shoot me on the ladder, the hardest part of the run

There's not enough of a difference between the difficulties to warrant separate categories. The only two that matter are Rookie and Professional as those are the easiest and the hardest. Besides, the sniper% and the kill everyone% seem kinda nuanced to judge correctly. Especially for something that doesn't seem like it would be that popular, it wouldn't be worth making it official. They can just be for fun and non-competitive.

As for any categories that I personally would like to add, I actually don't think Rookie SA is that bad of an idea. I have personally run both Pro/SA and Rookie SA and there is significant enough difference. In addition, I have done runs called "All Firearms" which involve collecting all the weapons in the game needed to get the "All Firearms" Achievement. If more people would be interested in this category to run it, it could be worth adding.