Boxer means flat, or did I miss something? I always thought that a flat engine was a boxer engine...

I think the thing is more that AWD is useless on a Cayman; It is mid-engined, very easy to drive, so nobody needs it as an AWD. It is not the case for a tricky rear-engined 911! It furthermore has no LSD (the 911 always had, but now needs to be Sport-Pack without PASM or GT3 to have it )...

So the Cayman won't be AWD because nobody fears its drivetrain.