My first proper road bike was a Holdsworth Avanti, the frame was made of double butted 501, I think it was the first bike Holdsworth made in 501 tubing. It was their entry level bike, so not particularly exotic but I definitely remember that the Avanti fork and frame was lighter than Holsworth's cheapest double butted 531 frame and fork at the time. So a 501 frame while no feather weight won't neccessarily be that heavy.
My first proper road bike was a Holdsworth Avanti, the frame was made of double butted 501, I think it was the first bike Holdsworth made in 501 tubing. It was their entry level bike, so not particularly exotic but I definitely remember that the Avanti fork and frame was lighter than Holsworth's cheapest double butted 531 frame and fork at the time. So a 501 frame while no feather weight won't neccessarily be that heavy.