I imagine blade coatings are applied as a way to help prevent rust and encourage water resilience for the edge. It wouldn't make a significant difference from one coating type to the next but I don't think a significant difference is what manufacturers are looking for. some skin is oily, some is dry. Some skin is very soft to the touch and some feels a bit rougher. Each coating type will help blade productivity based on your face. This is why so many people have extreme differences when talking about a blade. I personally do not like the Personna lab blue or Astra very much. I absolutely love Gillette Platinum and Gillette 7 O'clock yellow. Voskhod is nice and I can get the job done with a Derby but cutting efficiency is lacking on Derby however the blade is super smooth so I can successfully shave with it. I'm not sure if this is the coating or if the blade edge is just very very polished.