Hmm.. I see what you mean, and that is how I envisaged it (I think!) but i truly have no idea how to achieve this...
Ideally it would look for a "map/player/whatever..." models. I had thought it would be easier with cl_minmodels set to 1 so you would only need two models per map (i.e. Leet and GIGN).
If it does not find the correct map folder, then perhaps it would default to the original model directories... not sure how this would work though.
Is this a big thing for a knowledgable person to achieve? (i.e.... not me! ???

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If this IS possible, I presume it would only be a matter of adding a new directory for hostages to be map specific too?