Thanks for the shoutout cjjoseph. I'm a product manager here at Egnyte. The OP's use case is right in Egnyte's sweet spot. Our storage sync technology allows you to synchronize files among multiple on-premises storage servers and the Egnyte cloud. We support granular sub folder permissions and easy AD integration. Your Egnyte account will scale easily to thousands of users and many millions of files/folders.

If anyone on this thread has further questions about Egnyte I'd be more than happy to answer them here.