3 things. 1) I kinda feel like AeroFS has taken so long to come out that Dropbox occupies a huge chunk of mindshare. It's almost as if AerosFS will need to spend a bunch of time answering the "why should I switch" question. That said, I would love to see AeroFS succeed as I am less than keen on Dropbox less than stellar handling of security in the past as well as their general security model. 2) This leads to my seco…
OTOH, most businesses don't yet use Dropbox (much) today. If AeroFS's market is the enterprise, they're competing with Windows file sharing/SMB/Samba, NFS, etc., not so much with Dropbox. It's a bit skewed in Silicon Valley and in the consumer market.
If the target market is enterprise, companies like Box compete there and supposedly have more controls. That said, Box does not have filesystem integration, the last time I checked.