Some short notes, especially since this isn't a topic that I know much about.
- My initial take is like tonedeaf's--they probably felt that their older statement was too categorical, given that B 5 D physically can be used with the so-called vertical capsules.
- Any windscreen will affect not only the frequency response but also the polar pattern of a microphone to some degree—and those effects vary not only according to the size and construction of the windscreen, but also according to the capsule type (pressure vs. pressure gradient and/or the ratio between the two).
- Schoeps has a variable "wind machine" in house which they've used for researching and measuring these parameters; some years ago their former chief engineer, Jörg Wuttke, wrote an AES paper based on their findings, which I translated. But that doesn't make me any kind of expert on this topic; actually I have only a dim understanding of it. So I'll actually take some of the blame for the older statement about the B 5 D, since I wasn't knowledgeable enough to suggest something better, back when it was put into the catalog.
The perception some people have of Schoeps microphones as "muddy" is a side issue here, but I think the main reason is acoustics: In any given space there is a distance beyond which the majority of the sound that you can pick up with a microphone will be indirect. When you often record from beyond that distance, depending on the characteristics of the space, you might reasonably prefer the false clarity that can be caused by distortion and peaky treble response. A microphone that is objectively "better" may not be what you prefer for that situation, even if you would choose the better microphone under better acoustical conditions.
Plus, commercially more microphones are designed for speech than for music, and also for casual placement; meanwhile most naïve users tend to think that a microphone with elevated high frequency response has higher "fidelity" (sounds clearer, more detailed). So over the decades there has been an overwhelming market pressure to produce microphones with that type of response. It is actually rather difficult to find microphones that
don't have it.
The business of so-called fast transients is also a side issue here; I'll just say that the widespread audiophile view of this issue is, so far as I know, entirely unfounded in physics. Two linear transducers cannot have the same frequency response while one has "faster" or "slower" transients than the other one. When people say that they hear differences of this kind (as with people who claim to hear phase response at high frequencies), I suspect they are hearing real differences in frequency response and/or distortion, but putting a fancier theoretical construction on their perceptions of things that are more basic.
--best regards