After further thought and going "d'uh" over my own blindness, I have come to the conclusion that shades has the same subschool restrictions as Shadow conjuration, due to the afforementioned Epic Warlock Article.
In the Article it says the same as the spell description and no subschool restriction is given.
However, due to teleportation and plane-shift being part of conjuration, a full access to conjuration spells would leave the warlocks Dark Transient Epic feat to be completely pointless. (It gives you greater Teleport and plane-shift at-will) Unlike normal Spells, Warlock SLAs are at-will with no daily limit, so even an access to a teleport that works 80% of the time, would nullify the other feat. This has lead me to believe that the shadow-conjuration restrictions still apply (as far as RAI is concerned).