For me it was a vast improvement. I found that the center speaker, which had a big mid-range presence, really muddied up the sound of the Sony to the point that it was often like listening to mono rather than stereo. To compensate, I had shifted the balance/fade pretty far in the cabin. This diminished the center presence but also the other front speakers as well and while you could tell that it was in stereo, it sometimes sounded as if it was coming from the car behind me.
Five minutes (and a plastic trim tool) and the above problem was gone. Speaker out, disconnected, plug stowed, speaker in, balance reset, problem gone.
Now it's easy to distinguish between the left and right channels and having the balance set properly lets me really enjoy my Sony system.
It takes very little time or effort to do and is easily reversed - give it a shot and see.