Just read a test article in Shooting times. 1/3 less recoil and great terminal performance without ricochets or punching holes through building materials.

 

http://www.polycaseammo.com/products/polycase-arx

 

 

 

reading the link you posted....this line seems to be counter productive to the goal (stopping a threat) . "The non-expanding ARX® is injection molded from a specially blended copper/polymer matrix that........" isn't that like jumping back a century? because this has "flutes" it makes it better performing than a fmj?......not talking from an over penetration stand point....

http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CB8QtwIwAGoVChMIq9q_yYawxwIVhBU-Ch2vHQmQ&url=http%3A%2F%2Fwww.youtube.com%2Fwatch%3Fv%3DJ7_C6kNfjiA&ei=kcrRVevNE4Sr-AGvu6SACQ&usg=AFQjCNGqExaHCX-G9lUj8629Ag2hXJvp9Q&sig2=6pQiQZx_TPA2WCyE5P-alQ&bvm=bv.99804247,d.cWw

I would go for a heavier bullet...  The video mentioned the rounds veering off course for no reason...  In a short barreled defense pistol, I would prefer to have the heavier bullet and normal recoil as well...  Who knows how the rounds will cycle if there's 1/3 less recoil.

I wonder how they would work if they used powdered tungsten in the polymer. 

 

Looks a lot like what you'd get if you made a mim bullet, but didn't sinter it.