It's hard to pinpoint but let me see if I can explain it a little better. Because the gears are much farther apart in 1st to 2nd than say 5th to 6th, there's a higher range of RPMs. With the CDV, when you let off the clutch, RPMs move around much more in the 1st to 2nd gear and therefore there's a lot more room for "error", resulting in a jerkiness. However after the CDV delete, if you can drive stick properly, you can almost place the RPM exact where you need it, drop the clutch, and give gas and go, without any clutch slip.
The result is that 1st to 2nd is much smoother because you can get up and go at a faster rate without the RPMs moving around while the clutch is being slipped by the CDV.
Yes, its a very minute difference that a person will never notice unless you drive the car daily and drive it before and after. But the car definitely feels more natural now, and I am able to quickly change gears and start from a dead stop without feeling like I'm going into first gear every time aka with some clutch slipping.