Colin has a great point. Going that low does put extra stress on axles, control arms, and tires. You're wear will increase if you dont have a way to correct the camber issues.
As for the B&G's I would talk to Cav B5. He has these springs matched with Bilstien sports IIRC and he likes them. IMO, they are more harsh then my coilover setup. Cav agree's to my findings. the ride is stiff, and it looks really nice but there are pro's and con's to it all. BTW, it does lower the car about 2 inches in the front, and about 1.75 in the rear. Real aggressive look.
HTH,
Steve