I doubt very much that presence of PAT files indicates hardware mixing support. PAT files are for GUS MIDI engine. For instance, Miles GUS MIDI drivers support PAT loading, but I don't think that Miles GUS PCM drivers support hardware mixing, since Miles has an unified API, and its mixing routines are residing at API level, not at the driver level. However, I am not completely sure, because there are no source code available for Miles GUS drivers, but there's little chance of hardware mixing done by a driver.
This is how it looks in AIL for PCM sound:
Game
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AIL API <- mixing is here
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AIL driver (gf1digi.adv)
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ULTRAMID API
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GUS
For MIDI music:
Game
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AIL API
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AIL driver (gf1midi.adv) <- all messing with PAT files is done here, AIL API even doesn't know of their existence
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ULTRAMID API
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GUS
For MSS drivers (ultra.dig, ultra.mdi) it's the same sans ULTRAMID.
I realise that Creature Shock is not based on Miles libraries, but anyway.
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