nirad,
I have had the KL3 & KL5 heads on the E1e & E2e & L4.
I have only had the KL5 head on the L1 & L2 (with interesting results). Other than this, I cannot say. The E1e/KL5 or, the L1 or L2 with the KL5 are the only combos that make sense from a size/purpose standpoint. It is the old story - "just because you can, doesn't mean you should". Unless an E1e/KL5 or L1/L2 KL5 size or versatility is sought, why would you?? It IS fun to play however, and I definitely wanted the conversion capability, so I regard the McE2C adapter as a necessary accessory.
Hope this helps.