MA code lists it as 200lbs./sq. ft. for concrete with stone aggregate for the purposes of computing load on footers. (At least according to the instructor in my GC class.)
Breaking the block up was a two step process. First a 4" score line was cut with a gas powered dry masonary saw. Then the seams were all cut with a Hilti 902 Electro-pnuematic demolision hammer.
About 5 hours with the saw, about 6 hours with the hammer.