page, first I should "disclaim" that I've done a lot of translating and editorial consulting for Schoeps on a freelance basis, but I have no particular formal relationship with the company and am certainly not a spokesperson for them. My views are pretty much my own (or at least I like to imagine that they are).
That said: Some time back I asked the same question of two engineers at Schoeps, but they aren't the people who made the decision 40+ years ago. So I can only give you my impression of their impression, or what they chose to share with me--which is basically that the push-pull capsule design brought additional complexity without any notable sonic benefit. And I don't know whether it's a coincidence or not, but the capsules which used this design are among the few types that Schoeps won't accept for repair any more.
In March, 1981 two leading engineers from Sennheiser presented an AES paper which set forth the theory behind push-pull capsule design. The objective findings of that paper aren't in any dispute that I know of: A push-pull capsule can have lower distortion than an otherwise comparable design that isn't push-pull. But the push-pull approach, by itself, is no guarantee of either a low distortion figure OR of a good-sounding microphone. It isn't clear to what degree the distortions canceled by a push-pull design are ever audible in capsules that don't use the technique. The 1981 paper didn't discuss audibility, and I for one have seen no further papers on this topic. Opinions, sure--but facts, not so much. And this seems a mite strange to me.
I wonder whether Sennheiser engineers ever made comparison recordings while they were developing their capsule designs back then. They could fairly easily have made identical microphones with and without the push-pull technique, and then recorded the same music with identically-placed microphones of both kinds.
If that were being done today, they could even make stereo recordings with both kinds of microphone on a four-track digital recorder, then subtract the one recording from the other to hear just the difference (presumably the distortion that the push-pull design cancels out). That's something that I'd really want to hear before forming too strong an opinion either way about this.
--best regards