> NFS lets you share a directory between multiple servers (think of it as Dropbox for servers).
So, ignoring that NFS is nothing like Dropbox, there's nothing wrong per se with using NFS on a cloud setup for shared storage, this setup assumes that your NFS server will always be up. For anyone who has worked with NFS servers, you'll know that this isn't always the case. (Who here has lost a day when your NFS mounted home directory won't load?)
And you don't want to deal with a down NFS server when you're trying to auto-scale. Somewhere you'll always have a single point of failure, but I've always tried to make NFS not be it.
Oy vey. ;)