"The seller claims this watch is very rare."
If I've seen a seller say this once, I've seen it a hundred times... Rare is how I like my steaks cooked!
This definitely sounds like a "Buyer beware" situation to me, but I'm aways skeptical.
I like this watch. My 2 cents, having modified my own watches, I don't see a problem with this. All he did was switch the guts out of one MOW and slapped it in another MOW case. I think the whole thing is okay. I don't know that I would pay $800 for it, but I would buy it for $500.
Actually it looks like they changed the rotor as well IMO, but I could be wrong.
https://www.shophq.com/Product/647-190