Hi Marcus, saw you ragdoll stuff, pure awesomeness! Regarding your questions, HumanIK is IMHO only good for retargeting animation(mocap) data in Maya. It is integrated in aniMeta by creating a hik character along with the actual rig and than there is an extra group with a pairBlend on each relevant control so one can dial in or out the hik effect ( "mocap" attribute on each control ). This allows one to animate/tweak the mocap data, ie for foot locking. I have not implemented a baking step, yet, I guess that depends if it gets becomes a priority for some reason, so far I had exported the animation then directly to game engines, mostly UE.
Your question regarding a comparison to other solutions is very interesting, as it touches the design choices made. There are already a few options for auto-rigging out there, why bother putting out another one? First, the key idea behind aniMeta is simplicity with having novice users in mind. In my experience it can be already a challenge for users to install a script/plug-in. My idea was to have everything needed in a compact format with no dependencies/build/platform/installation issues, that is way I made the choice that aniMeta needs to be a single text file that can be started from the plug-in manager. Second, regarding features, the biped template would probably be considered basic when compared to other options out there, especially mGear. but that also makes it fast and has only what I consider the most important features to get some decent game animation loops. It is also vanilla Maya, so a rig created with aniMeta can be opened on another machine that does not have the plug-in installed. That is also a difference to mGear, which uses custom nodes. So IMHO mGear is definitely the choice if you need to customize stuff and want advanced features, aniMeta is more of a light-weight but fast solution, but offers some neat features that maya make it interesting for character TDs. For example. there is a tool to export/import hierarchies(json), there is skinning IO(json) and a procedural build system, which I used last year to build a couple of mGear characters with. So it complements Maya where I see some Maya`s rigging features lack and aniMeta can easily combined with other rigging tools and solutions out there. Some students told me that the smooth weights tool alone already makes it worth having around.
I know there isn`t any info about usage of aniMeta yet. But I am in the process of putting info stuff together so people can get a more specific idea of what it is and how to use it. But so far thanks for your interest! : )