YES! Thats the whole point for my company at least

Yes, please!!! To add, this would allow you to keep unsupported/non-media files together with the media assets that are viewable in Replay. Unsupported Adobe files could still reside in the same Dropbox folder but not be synched/viewable on Replay. But when it's time to share or deliver, those non-media assets could still be part of the folder that the client downloads.

It would be nice to see a 'Reply' folder in Dropbox that we can add files into, seeing as Reply uses our storage allocation anyway, it would reduce the duplication issue, and also make it easier to share download links with clients.

The only question I have is around how this would work with teams? I work on a project with another editor, and we both populate Replay with our edits: would this act just like a shared folder in Dropbox with edit permissions etc?

This would remove so much duplicate work and human error for our team.

Yes, bi-directional sync here would be amazing. So I can upload files into a Replay folder on the Dropbox desktop app, to then see it automatically populate into Replay.

Completely agree with this. I can't use Replay because all of the files are duplicated now, and I need the files structure inside of Dropbox as a company; not some files in Dropbox and others in Replay.