I hate Medium and I wouldn't let them be my primary distribution method for content but I would dual post. Is there a reason why you wouldn't just xpost from your blog to Medium?
Also, Google probably considers having duplicate content as plagiarism and your blog might rank low. The alternative may be post on your blog first, then post on medium in a couple days.
Would love to see actual data or even anecdotal examples of what happens when people crosspost to Medium and properly setup canonical links.