I had a chance to participate in my local PCA region's autocross school this past weekend - one of the events was a "skidpad" exercise to take the car to the limits of the friction circle, and to learn to steer with the throttle instead of using wheel movement.
After a few fast laps around, with the car refusing to skid despite increasing speed, I realized the PSM was still on
- once it was shut off, immediate massive tire squeal and dramatic sliding ensued!
The amazing thing was that, other than for the lack of sliding/squeal, there was no "feel" that the PSM was doing something to change the handling. It all felt normal, albeit a bit less dramatic - but I'd be perfectly happy to trade off some drama when encountering a tight wet offramp a little faster than desired in the real world...