No, have not read about the Gnostics there.
But. I do know that some gnostics have a much darker view of the OT God, that what you describe.
Some claim that when Jesus said "Ye are of your Father, the Devil" he was in fact referring to Yahweh, that Jesus came to reveal the Most High as the True God.
This guy uses a lot of hyperbole, but in essence, this is a gnostic view:
Also see Samael and Yaldabaoth.
"Do you believe man is created in God's image?"
"Yes," Fat said, "but the creator deity, not the true God."
Fat said, "That's Yaldabaoth. Sometimes called Samael, the blind god. He's deranged."
"What the hell are you talking about?" Philip K. Dick, Valis, 1981
"One problem with Yahweh, as they used to say in the old Christian Gnostic texts, is that he forgot he was a metaphor. He thought he was a fact. And when he said, "I am God," a voice was heard to say, "You are mistaken, Samael." "Samael" means "blind god": blind to the infinite Light of which he is a local historical manifestation. This is known as the blasphemy of Jehovah that he thought he was God." Joseph Campbell, The Power of Myth, p.76, 1988