I performed the update on my 396XT and one of my 996XT's. For SAFE-T, there is a slight improvement if you set the P25 adjust mode to 11. I haven't had much of a problem with SAFE-T in the past but there is a slight improvement. I tried it on the Boone, Hendricks, Clinton, and Montgomery county SAFE-T towers.
With MECA, I haven't played to much with it but if I set the P25 adjust mode to 8, MECA seems to decode much better, but doing that causes SAFE-T to decode with higher error numbers. That's why I wish you could set this per system, not for all systems like it is now. I'm also in Boone county and not in Indy. Normally, I can't get it to lock on MECA with just the Radio Shack duckie antenna, but I was able to much better when I made that setting 8. But like I said, I only played with it for a few minutes.
If you want to know what it's like before the update, you just have to put the p25 adjust mode to 3 which is the default.
I also left the p25 adjust level at 50.