I have been using the Ha-Ra Floor system for over 25 years and always thought the 42 cm large one cleaned faster as it has such a large surface span. First the yellow to dry dust then a wet floor pad. My choice actually was the green floor pad for all my floors as I had small children and dogs and this floor pad seemed to do the whole job satisfactory for me.
Now I am older in my late sixties I discovered that the 30cm was quicker and lighter to use. I found I could really scrub and get into small areas not to mention my old shoulders. For those who have furniture and rugs that you need to g around the 30cm seriously is faster.
We have just had the whole house tilled with a non-slip tile so after the builders left I had to scrub the floors. I certainly found the 30 cm did a better job as it had more traction on the surface, we even washed the walls down with the dry yellow to remove the dust before painting. I found the 42 cm rather large uptake walls with less control.
So, from me: Thumbs up for the 30cm if you have furniture and mats around. The 42 cm gets a little clumsy if you are trying to be flexible. I have always used the 30cm in bathrooms it washed the tiles which are to the ceiling. I only used the 42 cm in the cleaning business for large vast areas.
For those people who want a floor pad that is thick and sucks the dirt into the floor pad you can not go wrong with the yellow and green floor pad. You may wish to add the Pressbutler Squeeze Bucket to rinse and squeeze the water out, instead of using your hands. I have arthritis and now im older find the squeeze bucket easier than my hands to wring the floor pads out. The 30 cm Floor System including 3 Floor Pads is now available on Special for only $249