I would argue that this one was more sophisticated: http://pferrie.tripod.com/papers/zmist.pdf

What I am seeing lately with malware is increasing decline in sophistication, today malware is lame compared to the malware created around 2000. I would think that level of low level knowledge is rapidly dropping. When there were still real file infectors, there were some serious nasty technologies involved (btw, todays ransomware is a very old concept (http://virus.wikidot.com/onehalf) but it was used to prevent virus removal instead of making money).