How does FPC compare to mammalian rennet? How does fermentation-produced chymosin (bio-chemically engineered rennet) compare to real mammalian rennet? Does it affect the flavor of the cheese?
it’s also known as recombinant chymosin. Per wikipedia:

FPC contains the identical chymosin as the animal source, but produced in a more efficient way.

Since it’s essentially produced by the same genes, the molecular structures of both products should be identical, thus the results.