I think you need to read my post again. I wrote exactly what you mention, that K is less chiseled and with a rounder toe than U. I only compared the two lasts with each other. K is a chiseled last, with a rounded toe (not quite soft square, not quite round).
Crockett & Jones 337 is a last that isn't chiseled but with a soft square toe, for example.
May I ask how different is the fit (K vs. U)?
Sorry this question may have been asked a million times. I've only owned U last but tempted to try K