Get the 850.
I've checked out the 65" V10 before at a local Magnolia, the exact same TV you want, and man were the settings on maximum overdrive. Which one looked more accurate? Ok, either will look superb in your room. Well, in different stores, and not quite the 850, but the closest thing in the 800, well . . . I'd say the "OTB" of the 800 looked better to me than the V10.
Next time you go, ask them to put the V10 in THX mode. You will see that it will be significantly dimmer. That's often what "accurate" does to a TV. In the end, you can set it however you want, really.
I'm sorry, $2k is not worth it on its own for a better AR filter. I mean, if that REALLY mattered to you, you would instead get the $6,000 Z1, and that's only 54", IIRC.
Get the 850 pro calibrated. You will still be at least 1.5k ahead, perhaps most likely 1.7k ahead. Make sure to log at least a couple of hundred hours before splurging on the pro cal.
If you prefer, perhaps have the TV/STB calibrated for day viewing, and bluray calibrated for night viewing.
850 + Pro calibration = most likely the best TV you, or anyone you personally know, has ever seen.