Hey Ian,
I don't think that the seperator is full with oil unless the return is blocked. So you shouldn't have oil gushing out of it when hose removed.
Seperator's job is to capture the oil from beneath the valve cover and return it to the oil pan. So the oil will leak with engine running.
It wouldn't hurt to clean the seperator out IMO, since your hands are dirty already by now. It will take some time though, not a 10 minute job.

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Art.