yeah i could see how different suspension/alignment tuning would warrant various diff settings too. I think everyone just got what they are comfortable with.
I spent a lot of time trading tunes with B2B when he was around, I used to run higher settings before too (not too high, more like 35/70) but then some of his tunes had really low diff settings. Lately for race cars I start out at 25%/50% then fine tune from there as necessary. It definitely depends on the rest of the suspension setup too, how loose it is as to how you tune the diff.
The miata is at 25/50 and feels fine, even understeers a bit but thats a suspension issue I think. I have been blaming the tires in my head.. My soon to be revealed build is currently 25/50 and I think I need to bump up the decel at least to limit the lift off rotation (the car turns in much better).
I've had a race car or two with really high settings and you definitely have to feather the hell out of the throttle out of turns. I find I don't have to do that nearly as much with a lower setting. I mean you still have to roll onto the throttle enough to keep traction as necessary but when a wheel spins a little its not going to make the whole back end kick out. I have an easier time running part throttle with the lower settings
Off Topic: My drift cars always are 65-75 decel, 98 accel.