Sharp blades (eg Feather, Personna) for mild razors (think Merkur 37, Feather AS-D2, Rockwell plates 1-3)
Smooth blades (eg Lord, Derby, the various Russians...), for efficient razors (think R41, Fatip, Rockwell 6+)
This is especially evident with something like an Artist Club razor (the logical end point to high efficiency is just a bare blade!), where going ATG on the first couple of shaves with a Feather blade is quite tricky and requires special care and attention to have a chance of avoiding weepers / nicks. But after that, up to shave 15-20, the sharpness has been moderated and it's all good (relatively speaking). IME the cheaper DE blades are already smooth (aka not very sharp), so it doesn't matter much how aggressive the razor is if you have a less aggressive blade to start with. I can't speak to vintage blades (not personally interested).
But if you're looking for ATG BBS results from a 3 pass shave as fast as possible, with the least damage possible, IMO nothing beats a very sharp blade protected by a mild razor. This is why so many people say that a Feather AS-D2 razor only really works well if you're using Feather blades. It's too mild for anything else.
