I found it interesting that Sobell still claims innocence. I also found it impossible to follow his reasoning. I'd have to do an incredible amount of research - which I'm not prepared to do.
My view is that the Rosenbergs were a small piece of the Cold War. Many spies were operating. If the Rosenbergs were guilty they got what they deserved. If they weren't they got what someone else deserved - because there were many, many spies trying to do what they were accused of doing. Since the basic science was known to everyone the Soviets were going to succeed...sooner rather than later. They were good enough. They put Sputnik in orbit before us. I've read in many places that the really difficult thing was to prove that such a bomb was possible. Had the Nazis known it they would not have given up when they did and might have beat us to it.