BGF DRs definitely have better traction the Nitto DRs. The only problem is that the BFG DRs have a terrible tread life on a street car. If you want tires for the track BFGs are great. If you want tires for the road Nitto's are better unless you want to replace them every month.
I can't tell you in comparison to BFGs, but to F1s.....which I think you mentioned in another thread you are currently running......they made a world of difference to me. I know I still need to learn to drive this car right, but when I put them on this weekend they kept me about .5 faster than anything I could do with F1s. I put the 315.35.17 on and they handled great on and off track.