Wow I'm getting the Umoupen hype; Wanted to try anyway, but def now; It seems to be getting all the boarding and animatic features, implemented intuitively (*cough* SBPro..)
Umoupen has top-tier storyboarding, you can organize and sequence multiple shots each with their own timeline, split shots, loop them, add custom note categories, use a selected note for subtitles, and view them all in a thumbnail grid you can draw into directly and export as pdf