IMHO, the primary advantages of shell cordovan shoes are the material's innate beauty (that deed lustrous appearance), durability (the shoes never seem to wear out. my oldest have been in service for over 25 years and shoe no signs of failure!) and ease of maintenance (a quick wipe and buff before and after each wearing and the very occasional, light polishing).
I would also second rebel222's suggestion that you consider the Alden LHS in shell cord, as the best option for a penny loafer.
I would also second rebel222's suggestion that you consider the Alden LHS in shell cord, as the best option for a penny loafer.