I don't have a 7850 but I did buy both an HD 7770 and an HD 7790. One of those cards will go into my workstation to replace a GTS-450 to run JRiver ROHQ... MadVR. I will see what happens. My main HTPC is currently running the 7770. I have cycled through the intel iGPU and a GTX 545. That box was used almost exclusively for ATSC and Ceton Cable under WMC. Intel looked okay but there were times it struggled performance wise. The Nvidia GTX has an audio bug with certain cable channels either playing commericals or any content from the specific channel. I really like the Nvidia and if JRvier MC was production ready to replace WMC for all my Live TV needs I would have switched over to JRiver instead of buying the Radeons.
It looks like JRiver is developing TV playback usability faster than I expected. MadVR for live TV is the bonus... but I will be quite unhappy if I find that MadVR just doesn't perfom as it should on the Radeon platform.
An overclocked HD 7850 is a stout GPU and should support a very high quality setting and playback with madVR.
Mits WD-92840 92" DLP - Lumagen Radiance XS, Martin Logan Motion 40s, Ascend Sierra 2s
Older 58" Panny Plasma -DVDO DUO, JBL Studio 530
Pioneer AJs, PSB Images, Usher S520, JBL HLS-610, Definitive SM45, MusicHall Marimba