In previous sessions (before ORC) with Edgar, he recommended carrying out RC in the other programmes prior to running the BACCH filter. With GLM and the W371s, it would be pointless to not calibrate them prior to ORC - they are designed to be calibrated for either linear frequency response, reduced reflections or constant directivity.
For now, I've opted for freq response coupled with the Olive curve. There is almost certainly a significant attenuation with running multiple RC programmes (with the Olive curve, I get -7.4dB) but it still works for my use case.
One thing I like about ORC is that it shows the actual FR after the filter is applied (the faint orange and grey lines in the plot above). Another thing - going through this calibration process revealed that to me that there are significant differences in FR at the ears based on minor changes in listening position, but the head tracking of ORC takes this into account (unlike GLM).