I haven't seen anyone use them as a target rifle, if you're meaning as a competition rifle.
My father has a BAR in .308, and it's pretty accurate... 2-1 MOA. Recoil is lower than you'd think for a lighter rifle. My AR10 is more accurate. It about ties my M1A, though I'm using irons on the M1A and he uses a Nikon Monarch.
Then again, we've never put it in the hands of a really good shooter with really good handloads. Only factory and surplus so far.
I've no experience with the SLB2000... never even seen one.