I do wish the Brash Monkey guys the best of luck with their projects, but IMHO they focus on fancy features without having solid basics first. In their Kickstarter project they blur the lines between game toolkit and animation tools. Doing those things makes their projects very ambitious, especially considering their historical progress on Spriter.
FWIW, Spine development started 9 months after Spriter was first released. We needed a skeletal animation solution for our projects and Spriter couldn't do it. It has now been more than 7 years and you can compare state of the two apps.