The good thing with the FNAR is that it is about $1800 less than a SCAR 17. You can buy two FNARs for what you pay for one SCAR. As far as accuracy, my FNAR was fine out of the box, and will shoot 1 MoA (with certain factory ammo) all day long. I reload, so hitting the 1 MoA is also not a problem. I have seen some photos of targets from the SCAR on here that would rival anything I have seen from the FNAR. It seems they both like the 168 gr FGGM.
As someone else pointed out, the FNAR uses its own magazine, and they are 2x the price of a SCAR magazine. $50-60 is the going price for the FNAR 20 round magazines.
The advantages of the FNAR is that is comes in a 20" barrel (16 is also available), so it takes advantage of the .308 caliber a bit better than a 16 inch barrel. Probably does not matter much out to 400-500 yards, but the extra velocity from the 20" will help with kinetic energy on impact as well. There has been rumor (and it seems that it is coming true) of a 20" barrel for the SCAR, but that will likely add $1000 to an already high price tag. The FNAR is also a solid stock, so there are fewer moving parts, which adds to the long term durability (not that there has been any issues with the SCAR folding stock yet).
As for hunting, the largest game that I have taken with the FNAR is a 450 pound black bear. It was ~150 yards, and it only took one shot. Could have probably used a SCAR with the same result. Have now taken 4 white tail deer with the FNAR, they were all single shot kills. If you are looking at using it for hunting, make sure to check your laws on magazine capacity. 5 round magazines are available for the FNAR, not sure I have ever seen one (unless modified by the final user) for the SCAR that was less than 10.