Should I update my arXiv submission after it's been reviewed and published OA in a Springer journal? I recently had a paper accepted in a Springer journal, which allows "Open Choice", meaning that the article can be made Open Access. My institution covers the charges, so I agreed to do it and now it's in process of publication. 

My question is: when I first submitted the manuscript, I also put a version on the arXiv and on my webpage. Now in the accepted version there are a couple of updates coming from referee revisions. I already put the new version in my webpage, since I know I can do that. 

But what about the arXiv? When using non-Open Access, there is a 12 month embargo period. But it's not clear for me from
https://www.springer.com/gp/open-access/authors-rights/self-archiving-policy/2124
whether I can update the version with the accepted version in the arXiv. I don't care for the journal typesetting; I'm happy with just putting the revisions in my own LaTeX file. 

Can I do it without issue?
Under Springer Open Choice, you retain copyright and the journal releases the published article under a CC-BY license.

So:


By the terms of CC-BY, everyone can make a copy the published paper and redistribute it under the same license, including on Arxiv.
Even better: you, the copyright holder, can relicense the paper to anyone, with the terms you want. As long as you don't give them an "exclusive right to distribute", of course, because you cannot take back the rights you have already granted others.


Some Open Choice journals use CC-BY-NC, though which may make redistribution under the first method trickier, because Arxiv does not have an option for CC-BY-NC. The other method is always ok, though.

Note: I am not a lawyer.