cgfan wrote:I found that with all of my pulls the cooled basket resulted in noticeably more crema and body, with an improved taste (particularly in sweetness) over the conventional shot.

Two comments:
1. The faster one preps one's shot, the less time a "hot" basket will have to affect the dry coffee. So the effect you notice must be somewhat dependent on barista speed.
2. It sounds like you are still using a spouted portafilter. With a bottomless portafilter, the bottom of the basket is exposed to the air, meaning that it's already somewhat cooler than usual. I just made some quick measurements of this: at idle, the center of the bottom of the basket measured ~140F in a spouted PF and ~105F in a bottomless. That's a significant difference.

My current method of temp surfing sort of requires that the p/f be locked in for at least 30 seconds before pulling the shot. I lock it in, open the steam valve, pull a cooling shot for about 15 seconds, then hit the brew button immediately after it comes back up to temp. I notice no discernable difference in the taste from leaving the p/f locked in for this short time.