To me.............A heavy dose of CS feels like I am stuck in the filter of a giant menthol cigarette. Not much of an effect, and I have seen people with no effect at all to it. The other factor to consider is that CS displaces oxygen and therefore, if used indoors, must be used in certain amounts for liability purposes, because it is possible to over-gas someone with CS.
OC has no tendency to displace oxygen, therefore, it can be used in any amount desired, without the worries associated with CS. Sometimes agencies/ precincts require a certain OC product to be used. If the officer was allowed oil based, high heat, higher percentage OC fogs, the effects would be absolutely brutal. Unfortunately , we live in a society which even dictates what spray an officer must depend his life on, because other sprays are inhumane.
OC in a good spray, will whoop some ass. Unfortunately the officers seldom use the stronger sprays on the market, for liability reasons, and so the suspects can de-contaminate faster, and be on their way.
-PC-