I think K models might be cool. I wish I knew more about people's objectives. If the objective is a quieter experience with Ear protection, the shorter cans make more sense. I did make some 6" M4SD-L prototypes, and we went straight to 6.5" OAL, but then later I took one of the 6" ones to the range and shooting with ear pro, they sounded great, and they were so light it was like they weren't even there, and they were a lot of fun to shoot. It sort of surprised me how fun the cans were even though the numbers weren't really anything to write home about. The cans were like 140DB.