Here's a few suggestions of mine from trying the trial version of spine.
Ability to set user defined hotkeys. Workflow wise, its nice to be able to access the most used keys all with one hand on the keyboard. the move/rotate/scale keys are far enough away from "set" key to slow things down. Also, being able to set hotkeys similarly to other software packages you may be used to EG: WER and S like in maya makes becoming more proficient with new software easier.
Pre defined key easing shortcut buttons. Being able to quickly press a button such as "ease in ease out" would save a ton of time in the long long run. Right now you have to change your key to a bezier and then drag the handles every time.
Easier way to copy / paste keys. Maya has a simple easy way to copy/paste keys. Simply start middle mouse dragging while over a key to the new location you want to copy to and press "set key" this would help a lot.
Hotkey to switch between frames (I like how you can already use W and S to jump between keyframes) however switching between frames would be helpful as well.
Also i had a question about the full version of the software, when you export seperate images, do you offer a way to define the size of the stage for the images? or does it simply export the images based on their center point. Or is there some other way to make sure that the animation stays in the same place visually?
In a jump for example, would the image appear to move upwards off the ground plane? or are all the images based off the characters root?
thx