That's what I'm sayingthe numbers don't match the picture.  I want my joystick to be more responsive around the center, so I use a negative value.  I move the slider to -2, and the picture shows just a small curve, but the aircraft are hypersenstive, and the numbers confirm this.  If I set the slider all the way to -15, the picture shows a dramatic curve, but the aircraft responds much more mellow, closer to default response, and the numbers also jive with this.  I'm not concerned with the setting number, ie -2 or -15, it just seems the response is opposite what the picture shows.  I'm happy with a setting of -12, now that I know what it's doing. 
It was frustrating at first, because I was looking for a small adjustment from default.  One click (-1) made little difference, but one more click (-2) made the aircraft almost unflyable.  It wasn't until I experimented so I could tell you the exact problem I was having, that I found I needed a lot of clicks (-12 to -15) to get the small change I was looking for. 
But I also discovered one click (-1) has the OPPOSITE response, and deadens the stick near center.  Again, I'm not concerned with the setting number, just using them as reference points.  And I'm not complaining --I've found a setting that works for me, just bringing your attention to something that doesn't make sense to a less computer saavy user like myself. :)