Can't go wrong with either IMO. It's like asking whether you want a million dollars in 100's or 50's. Both will bring a pleasurable result.
Love them both. I do think the 140's pull down less bass but sound more natural.
HOWEVER, Neumann has the newer series out, both analog and digital mics KK series I think?, and I have heard zero from them.
If you were going with the Neumanns, I'd say check into those.
ANOTHER THING, is you will probably be able to find a nice pair of 140's used, and the 8040's prob not.
Looking at it I thought the 8040's were more expensive but I am wrong.
Anyone know what the REMOTE cables go for $ wise. Remember they are NOT actives.
Personally, I'd go with the 8040's.