According to me, the major impact of changing the item category group would be the item category determination in deliveries. Specifically when you create outbound delivery for either the intra-company STO or inter-company STO, the item category will be determine based on the delivery type (NL for intra-company & NLCC for inter-company) and item category group (Eg: NORM) of the material. Similarly when you do the return STO deliveries, the item category determine based on the Delivery type (NLR for intra-company and NCR for inter-company) and item category group of the material.The item category determine in deliveries directly controls the picking and packing activities. Eg: If you've WM then the item category should be relevant for picking unless you can't create TO for stock removal and putaway.
