According to the owners manual, this rifle is rated for the SS109/M193/M855S cartridge...so perhaps that info relates to the twist rate.
My DA556 seems to be a quality piece. I suspect that you can't go wrong either with CanAm or Marstar...it just depends on what options you want.
Based on a bit of Wikipedia research, my guess is that these rifles will have a 1 in 7 or 1 in 9 twist, based on current. NATO standard. The old 1 in. 12 twist has been out of fashion for quite a while...