Very true, and here is E41k so that you can interpret those house rules:
http://web.archive.org/web/200703041813 ... /index.htmIn essence, however, there are not THAT many changes that come through in the army lists... basically there are a few new unit types (forward observers, repair and medics). The Horus Heresy lists are also potentially a lot larger and much more rigid than normal E40k detachments, due to the nature of the Legions' organization in the Horus Heresy era. Hence you get the "platoon" system mentioned on the site. You can, of course, throw this out the window or tweak it to your liking.
The Space Marine Legions list is nice, but I like the Squats and Imperial Guard list quite a bit too. You may have to click through the Wayback timeline to get those, but they are worth taking a peek!
What are the army lists that are missing? Maybe an independent Titan Legions list?