Ok, I'm talking about an observer that has not crossed, and is a sufficient distance away from, the event horizon. I don't know how you can say that we would not notice a change in g if the sun became a black hole.
As for the 5 solar mass BH and the 6 sm star, light could still escape from the star but not from the black hole. The gravity of black holes is infinitely stronger than that of stars. Unless there is something else contributing to the immense gravity of black holes, they must have more mass.
