Yes sprint + crouch will slide. It works the same as Spartan charge. You must achieve the speed lines to be full sprint before you can hit slide.
Oh, that makes sense! I've haven't seen anyone else use it MP, so I thought they nixed it. Stability I accidentally found, but knew it was in as I saw other players executing it.
Last night my aim was all over the place. It almost felt like someone turned my sensitivity way up and had a lot of trouble putting the cross hairs on target on certain weapons.
With the qualifications almost done, my rankings ranged from Silver 1 (FREE FOR ALL) to Platinum 1 (SWAT) with gold on all the other modes in Arena.