Hi Nate. First of all sorry for my english, sometimes i'm telling not the same what I think in russian =).
I don't want to blame unity-runtimes, and i more than sure that native runtime should work faster, and even if in any cases mecanim will be faster you will find the way how to optimise it.
Main reason why i made this package, because it's should be easier for artists to work with animator, than to go in to code and make some changes there.
here is a code which I made for that model in the second video
and here is default state machine
it support following features
run/walks depends on speed
in air up
in air down (depends on velocity)
[combo] punch left, right
[combo] punch left, right, upper-cut
throw (from any state)
complex jump with
maybe something else.
Don't forget that if you want to adjust some transition, or blending animation, you don't need to go to code, you can do that in the editor using native features.
Now just tell how many things you need to do as a programmer if you first time opened unity and trying to make something similar with spine-runtime. Sorry, i've tried just import to spine-runtime, but didn't tried to make any controllers.
everything you did can be done with spine-unity.
Have you tested performance difference on mobile devices?
as i told before, you're right, spine-runtime should be faster, but almost everything you need to do through the code.
Is it possible to use the state machine / flow chart stuff to trigger code? If so, you could use it to set animations using spine-unity.
No, i don't think so, in animator, you define state and provide animation for that state. But, from animation(which is native unity animation) you can. (more details here)
Sorry, i can't make performance test right now, and will be happy if someone will did.
I forgot to tell that in video, but there is one more thing. Because of using native sprites, for each sprite unique mesh generated, which reduce number of empty pixels what is good for renderer and increase performance
Probably you can achieve the similar if you will define meshes for each sprite in unity.