Negamages were in some edition, I think they were in 2e. ISTR 1e had naked Matrix (no deck, write programs on the fly, but take physical damage from all ice) which was fun and again somewhat abusable - I think our decker didn't run with a deck as he could write programs on the fly and they were better than the ones he could buy. I'm not sure about other differences between 1e and 2e.
I've never even read 4e, and I have enough SR rules and supplements to last a lifetime. I bought 3e and ran a couple of short games with it, but it seemed to have lost some of the flavor. Rules reading sessions and discussions were a different matter. I had principled characters and we never really tried to minmax while playing the game. I remember it fixed most of the most obvious system hick-ups in the first edition, mainly it got rid of the 'everything connects to everything' Skill Web (Throw a grenade with Charisma, at +12!) and the humongous list of languages.Ģe was still somewhat prone to system breaks, but it was still fun. I think 2e was the edition I played the most.