I can kind of understand the "Hearts of Steel" inclusion, but its placement in the volume order is odd. My prediction is that "non-G1" comic stories (Movie-verse, Armada and so on) may see print as "special releases"/editions at some point. Partworks often have these volumes that sit 'outside' the main collection, and if it's successful, this makes sense. Regarding GI Joe crossovers - I am sure I read that things like Dreamwave's WW2 crossover is being included. I'm not sure about the ORIGINAL crossover though, as it conflicts with "Wanted: Galvatron Dead Or Alive". It would be a shame not to include it somewhere (to be "Definitive"). But we've already heard the Movie Adaptation isn't being included, and only "certain" UK Annual stories are, so this already isn't as definitive as, say, IDW's Classics US/UK collections (flawed though they are) for the Marvel material.