I have a fairly low-end HTPC. It has an AMD E-450 CPU/GPU. It's plenty fast enough to watch 1080p x264 videos with DXVA, but not nearly fast enough to run Red October HQ (MadVR).
Let's look at my CPU/GPU usage (measured using the AMD System Monitor) when watching a 1080p x264 video with 6 channel AAC audio:
Red October Standard: 10%/20%
Red October HQ: 100%+
Red October Standard uses almost no resources at all, which is a big hint that it's using 8-bit integers in the video rendering pipeline. I wouldn't be surprised if a major portion of the CPU usage is dealing with the 64bit floating point audio pipeline and not even the video renderer!
Now let's look at my options with MPC-HC, which has some very neat options that JRiver should adopt.
baseline 8-bit rendering: 15%/25%
Baseline + "Force 10-bit RGB input" + "Half Floating-Point Rendering": 25%/45%
Baseline + "Force 10-bit RGB input" + "Full Floating-Point Rendering": 40%/70%
Using MadVR: 100%+
So, as you can see, MPC-HC allows a much greater range of video rendering options. Even my low-end HTPC can handle 10-bit RGB and full floating point processing. And yes, it's still compatible with DXVA!
The image quality, even using only half floating-point rendering, is far superior to JRiver. I compared several scenes in movies that featured a lot of fog and smoke, and examined the smoothness of the gradient. JRiver showed significantly more banding and color artifacts in every case.
It's a shame to have such amazing audio rendering quality and yet give no middle ground in terms of video rendering.
I would love to spend $40 on your media player because of it's superior WASAPI support and 64-bit audio rendering, but the poor video quality when compared to MPC-HC is a deal breaker.