Overcontrolled,
Methinks you miss the point; there is only one standard for certification of hoists (or any other 'human external cargo' lifting equipment). Only the operation of the hoist has a variation in standards - for commercial air transport (CAT) that includes OEI performance.
For other than CAT, OEI performance is not required; this also applies to HEMS hoisting - by alleviation, and SAR - by definition (i.e. not CAT).
Jim