First I do not know the limits of PSM. I wouldn't do anything blantantly stupid like cranking the wheel 180 at 100mph attempting to drift it...
Over the last few days, I've been purposely trying to fry my rear tires since I need to replace them anyways and practice some skid control at the same time. They were getting bald on the inside and one has a patch so that was my excuse for driving like a mad man in a big deserted parking lot for my stunt driving :dance: .
PSM is simply amazing. At speeds below 50mph (parking lot wasn't THAT big) , I could never get the car to spin! I did get it out of shape somewhat, but PSM would dutifully kick in and save me and point the nose in the right direction while simultaneously scrubbing off speed. Many times it did so without my being able to detect the edge or limit of adhesion, especially in the wet. As I honed onto that limit envelope I took off PSM and had some really wild rides. Attempting my impression of Tiff Needell, I easily found myself doing 180's and 360's without much provocation (bald tires) and overcorrected some slides. Saving the first slide too quickly often resulted in me spinning in the opposite direction. It made good learning for fast wheel manipulation, hand over hand steering vs. shuffle steering etc... (once at an auto-x years ago I rode in a 944 and this guy could drive like a MOFO! I mean I thought he over cooked just about every single corner but he would alway maintain control AND be fast! For months I made a dedicated effort of making shuffle steering a habit where ever I went, and I noticed he did the let-the-wheel-slip through the fingers routine like so many of us do intuitively when we first started driving. What I had just broken the habit of after doing it for years. When I asked if that was the "correct" and accepted race method for steering he responded, "it works for me". Anyhow back to PSM...
PSM was so good, I considered running the tires down to the cords, but decided that hydroplaning was not something I wanted to experiment with
and although PSM was doing a stellar job, I don't know what it would do on ice.
For me, PSM is a must have. It's a no-brainer, much like the S decision. I believe that in 10 to 20 yrs all cars will be equiped with such. Like ABS, for 99.9% of drivers, I don't think you can beat it. On the track, under a controlled environment, I do however believe it will slow down an expert driver a little.