If you're using SkeletonUtility, no.
Otherwise, yes.
Also, even if you plan to use SkeletonUtility in the future but don't need to right away, go right ahead.
But Mitch hasn't mentioned anything about when he's going to work on things and what dates he's shooting for or whatever so there's really no telling on that front.
22 Feb 2016 2:54 pm
If anyone's having problems importing their jsons after 3.0.11, you have to update your runtimes. (but you don't have to reexport your old jsons. There were recent changes in Spine-Unity that matches some changes in 3.0.11 but are still compatible with old jsons. But the old runtime wasn't forward compatible with these new changes)