I don't know. I definitely got a really good K4S compared to others I have seen on pics from the US. You don't get to see many around here live
but a friend of mine has one too and hers was even lighter than mine. The K4B were maybe a tiny tiny bit better, but this comes from our "expert" and he says he is not sure himself. His KK, which was mine before, is indeed a beauty. They sell them here in a shop for 79€ and I am now thinking of getting one before they disappear. The K4B: not so much...