Welcome to the club. I installed the LSD 2 months ago, after owning the car fora year. When just tooling around town the effect is subtle, but it's always there. You don't have to be tracking the car to appreciate it. (But it sure helps there, even with snow tires (it was so cold that day).)
There is a left turn coming out of my neighborhood onto a highway I take every morning. Taken it every day for 17 years in several different cars, often accelerating hard to beat traffic. The LSD just plants the rear end of the car and makes applying power while turning so confidence inspiring. Every day since I got the LSD, taking that corner now brings a little smile to my face.
Yes, the $2500+ for the LSD is stupid expensive, and I wish the car came with it. And it's no where near as fancy as the active diff in the M cars. But if you want a mod that makes the car feel and perform better, I think it's worth it.
Only downside is the completely stock pumpkin. Wish it had a M logo or something so you could look under the back and go 'ooh, it has the LSD'.
