I don't have my 850s yet (not until July/August), but I did listen to some in person before ordering.
Note, they were not fully broken in yet. The best way I could describe them was sharp. They typically didn't color the sound from what I could tell (except for a slight boost in midbass), but they were very exact when called upon.
They need to be paired with a sub if you want to do HT correctly. Watching depth charges or horses racing just isn't the same without the "below 30hz" attitude a good sub can bring.
The only other way I could explain what I heard was the comparison I did between digital coax and digital optical cables. Digital coax to me sounded warm and the intricate sounds flowed together. The digital optical cable sounded much more detailed and defined on the micro sound scale.
I have a suspicion this will be the difference you'd see between the swans and the rockets if you were able to compare the two. They both should sound fantastic, but it may come down to your preference in what sounds better.