Thanks to RC's encouragement, I hit the PSM button today and did a few test runs in the CT today. Here's what I've found:

1) Throttle "response" is no different (on my car at least) between PSM on and PSM off. At best there was maybe a slight difference but I think that could have just been normal variation between runs.

2) With PSM off however, my car tends to downshift into the proper gear more often. The best example of this was cruising around in 4th, in Drive, at around 40mph. Flooring the gas pedal with PSM on resulted in a downshift to third, a brief period of acceleration and then a downshift to second. With PSM off however, the downshift went much quicker to 2nd from 4th and spent virtually no discernible time in 3rd gear.

My car was built in 12/03 and has under 300 miles on it. For these tests I kept the revs under 4200RPM, I'm not sure if taking it up above 4200RPM would have changed the results any. I just thought I'd share.

I've got access to another CT that I'm hoping to try the same test on to see if I get any different results.