I tried it recently.

The H.264 DXVA support is awesome. While playing the Ducati video, my CPU usage is 2% with CoreAVC uninstalled to prevent it from being used to decode the file. The list of cards supported are available here. Unfortunately most of the ripped HDs (example: anime and movies) does not benefit from this, with CPU usage still the same as if it would have been CoreAVC doing the decoding work.

To force MPC-HC to use it's built-in decoder instead of Apple's, rename the .mov file to .hdmov.

I'll be looking at future versions of this player to see whether I can dump the old MPC and replace it with this.