No it is not. That's not factually correct. I have two 890SA and they are not 680 in disguise. Not the two I have anyway. I'm not sure how that myth got started, perhaps by Stanton's own slapdash materials, just as for some reason there was a rumor going that the XV-15/625E was moving magnet. No way, no how. Nyet, Nada, Niemals, Nein!
Quatsch!
Not to mention, the seller of those styli is selling the 890E, which is for the 890FS, which is known to be moving magnet and to which I can confirm. The seller is saying they work in the 680 bodies so that he can sell more of them. I have a feeling he's sitting on a boatload of them just wants to get rid of them. He got me to buy one even though I already had plenty just to check his claim. He said his 890E were of the last batch and so had smaller magnets that didn't cause hum. But to me, what causes the hum is the gauss, so even if the magnets are smaller, the magnetic flux should still be the same.
Guess what? It hummed. It's a very low hum, but it's there, and it's annoying. It sounds like a ground hum. In sum, the guy doesn't know what he's talking about--but he's got some nice styli for excellent prices. Just don't believe his sales balderdash.