Well, I did it, put the 91 oct, SC Sport package on my car, did the fuse trick, and took er a spin. I have driven city stop and go for about 15 minutes, so far no idle surges. I can tell the SC package is still enabled, b/c in D, 1st gear holds longer [shifts to 2nd at higher RPM].
Now, I'm not sure if it was the fuse 11,14,16 trick that has the same effect has taking the battery cable off for 5 minutes or not. I never did the battery disconnect method. Unfortunately, I did a couple updates at once: I updated my SC via USB cable, it was the first time I've updated in about 5 months. So I applied SC Sport package with the updated software and did the fuse 11,14,16 trick all at the same time.
I also did the ESPOFF
mode (the under/behind the shifter one, with a switch in the middle compartment - it's way easier and more convenient), so I was driving around with my ESP/BAS light on, burning rubber.
But, I didn't have any idle surges, yet. It's a good sign. It was driving my wife crazy, she kept looking back to see if someone rear ended her. I didn't like it either. I'll post again in a week or so and let you know if I've experienced it again.