Hi there,
From an SEO perspective, I think it is definitely worth implementing hreflang. If it were one of our clients, I would tell them that it was vital that they implement these.
We have had issues with clients where their web agency didn't correctly implement hreflang and the wrong international website was ranking. These tags are a strong signal to search engines, such as Google, of which country your websites are targeting. Some SEOs would even argue that the tags will help your ranking for those countries.
I would also be worried about duplicate content in this case, but I would strongly advise that the tags are added if possible.
Just make sure that they are properly implemented! Here are a couple of resources for further reading:
https://moz.com/learn/seo/hreflang-tag
https://moz.com/blog/using-the-correct-hreflang-tag-a-new-generator-tool
Best regards,
James
