Dunno what I can add to this conversation, except that Rush is considered to be the first 'prog metal' band as they were considered to be a metal band when they first came out. It doesn't really hold up to hindsight since they weren't heavy, but they were progressive and at the time considered to be metal. Yes and Genesis had a few 'heavier' tunes, but were not even close to being metal.
The first real prog metal CD was Watchtower 'Energetic Disassembly' which was totally metal and totally progressive. Most prog nowadays is just derivative Dream Theater fanboys, but some of them put out some good stuff. Andromeda is probably the best of that crop, since they are stellar musicians. Real prog has been renamed to either 'technical metal' or 'avant-garde metal'. Whatever, genre names are ludicrious anyway. Power metal? WTF?!!