Yes, it works great with no slipping. I first heard this tip about a year ago from 908SSP (alex ortner) and tried it on my s4 around the same time I purchased an evo slave and gp radial master. Out of the three, removing two springs reduced the pull the most. I switched the slave and MC first cause I was skeptical about removing two springs. The switch really did not reduce pull as much as I had hoped. So I then removed two of the springs and was very happy with the result, still a strong pull compared to the wet 620s clutch but much, much better than the stock dry clutch pull. But the other two items serve other purposes than just reducing clutch pull.
If your aim is to reduce clutch pull and your current slave is working correctly just remove two springs from the clutch (two springs that are across from each other, not side-by-side.). Its free. If you feel you need to reduce the pull more and/or your slave is leaking get an aftermarket slave in addition to removing two springs. GP radial master moves the clutch engagement point so you don't have to pull the lever in as far to shift/reach the friction point. Improves the feel a bit and reduces the pull a tad as well.