Hi Steve! sorry for such a late answer. I reckon the skills are quite transferable. The animation principles are the same for all forms of animation, and designing a good character is about developing a good "eye". If you draw a lot of faces, that helps with sculpting them and vice versa. Same with clay and Zbrush. So if the basic skills are down, moving between mediums of expression is just an adjustment if you change your mind later.
If it helps, animators I spoke with at Aardman reckoned it was easier to go from stop-mo to CGI rather than the other way around. I can't say from personal experience though, I've barely tried Maya, though I had a little bit of fun with Zbrush.
To me the magic of animation is making the plasticine I played with as a child come to life, so CGI just doesn't do it for me, but that's me.
Hope that helps! Good luck with your animation.