Sorry for intervening so late, I missed this thread completely ...
The HHRS is one of those computational modes on recent Olympus cameras. It has a "brother", the THRS stands for Tripod High Res Mode ...
I tried them both, and find them not very useful in daily life ... if the subject you shoot is moving even a little bit during the time it takes to make the shots, you get a blur on the moving parts ... so I find it useful only architecture (providing no trees in the view) and other absolutely static objects.
The .ORI file is in fact also a RAW file, it is just the first image of the shot sequence, and in such a life saver in many instances ...
I processed some HRS in the latest version of OM Workspace on my old but reliable MacBook Pro with an i7 processor (late 2013 with 15 inch Retina screen) and found the processing slow.
Then I processed the files in CaptureOne v22 (my usual RAW developper) although C1 state that they are not compatible with the E-M1X HRS mode. Apart from the problem with the blur (that C1 cannot correct of course), I can process the HRS files just fine but a little slower than a non HRS file (file size is around 75 MB, remember) ... so that is my way to work with both THRS and HHRS files nowadays ...
Note that I also use the HHRS sometimes when the camera is mounted on tripod ...
Here's an example of a recent HRS shot developed in C1.
Stay safe,
Rafael