Can you you post your article on medium after posting it on your blog? How would you avoid penalty by google for duplicate content?
Not being familiar with Medium, I took a quick look. It does look modern, but not I am not sure how it would benefit a company as much as hosting it's own blog.
I have seen too many people create blogs on other sites and lose much of why a blog is created. As a business, your goal is not only capturing readers, it appears that Medium will do that well enough, but creating engagement for conversion. When a blog is hosted elsewhere, you lose much of that and any search juice you create you have handed over to another site and cannot get back easily. It may be that Medium can attract attention to your site, but I would rather have the search traffic to the work I created on my site where I have full control and not hampered by what the blogging site offers.
For example, I know of an attorney who's site is terrible. Even if he fixed it up, his blog is else where with no real conversion options. Worst yet, he participates on another professional site which is excellent, but the site does not convert back to the website very well unless you click on the profile. It is likely that people who read his well written articles will be satisfied or think that is all there is. Few will likely click on the profile to go the website.
Personally? I would host my own blog and use software that allows me to engage and convert my readers to buyers or users.
It may be possible that Medium will do that. I just think the return will be much less than if you hosted your own blog. Just my two shinny copper coins.
The question here is; what is the idea of that blog?
If you want it to closely represent the opinion of your company, then you should host it and design it as one with the rest of your website, that way it always feels like it's the same.
If you want to use it as a communication/conversation mean, then Medium doesn't seem to provide that, so it's not an option.
If you want to write some content, but you don't care/mind that it is associated closely with your company, then Medium is a good option since it will attract readers who may not have the slightest idea who wrote the article since that information, although present, is not very prominent.
If you don't mind about the correlation between the blog/article design and you company site, then it may be an option, although remember that design is one of the elements to make something belong.
If you are interested on trendy design and don't have the time capabilities to make/install what you want, then Medium is a good option.
I can go on with a few more elements, but the general idea is, if you want the blog to be perceived as something that belongs and represents the company, then it should be on the company site/domain.
Also, you could present the content of an article or even the whole blog hosted on Medium inside your site, but I still recommend having it 100% on your site/domain/server.