[ddeflyer]

There is more to it than that also. Another major advantage that the DL has is that the car's gyros are hard mounted in a way that you are unlikely to imitate with a DL (basically short of fairly extreme drilling and bolting). The DL's mounts can effectively damp some of the finer details while the car's gyros will show it much more crisply. Same goes for the wheel speed vs. GPS speed; the wheel speed is averaged over a shorter period of time so you get more accurate information about when a delta occurred.

Beyond that, some of the sensors can be very helpful in training on other things. Heel toe is a classic one with training to not have a brake pressure drop or increase. Another tool like that is car balance; you can see when you apply brake or throttle and then see what the effect is (camera helps alot on this).