The product has come a long way in the past year. In particular, our Private Cloud offering is deployed at a number of large organizations, all of which are quite happy.
Regarding comparison with BT Sync -- I think their product is great, but we try to go beyond simply syncing files between devices by allowing for a lot more administrative control to the IT organization while still giving the users a really simple Dropbox-like syncing experience. Things like remote wipe, version management, conflict resolution, and so on.
But YC did not directly help us land these customers in the forms of introductions. For the most part, they've come to us through word of mouth and internal employee references.
However, if you want tight admin control, you may have some issues. For example: If an employee leaves, we're not sure how to revoke privileges for them once they have access to the folder.
So, I recommend very small companies use BTSync since it's easy and free. But if you're a larger company, you have probably outgrown BTSync and should get something like AeroFS.