I still have my doubts that this preloaded diff is making locked diffs obsolete...
Clutch pack is, afterall, a bit less responsive with the throttle. Locked diff makes use of really ridgid setups with hardly any play in suspension or roll, and if you are having a slight bit of wheelspin, it still is in control and pushing forward nicely. Clutch pack, with or without preload will always make the car feel like it has a slight bit of mechanical traction control, aiding the car in and out of the corners. One thing is certain, that the preload setting makes the cars a lot more enjoyable and believable with their performance, and feels like it should feel. Locked diff is just all wrong, and the only reason it should stick around as an option is to see if the tire physics have critical issues to be fixed. And they would have to be fixed if locked diff continues to be faster.
I hope a lot of people (especially hotlappers) make use of the preload setting and see if they can develop a setup to run faster than their locked diff times. It REALLY needs some extensive testing.