Choosing a Cloud Storage / Synchronization Vendor

When I worked at Socialtext in Palo Alto, one of the brightest people there was Alan Lepofsky, then director of marketing. Alan, who’s based in Toronto, now works at Constellation Research where he covers the enterprise collaboration software market.
In a recent blog post on File Sharing and Synchronization Services, Alan lists many of the key vendors that he’s tracking in this nascent space, including all the usual suspects (Box, Dropbox, Google, etc.)
But what really caught my eye was the list that he’s put together of the key factors companies must consider when choosing a vendor:

• The terms of service around ownership of the content you upload.
• Are there collaboration options (ex: comment, Like, etc), built in file viewers, or is it just cloud based storage?
• What OS/devices are supported: Windows? Mac? Linux? – Web? iPhone? iPad? Android?
• What other products/tools/services is it integrated with? Is there an app store?
• How much storage is offered? What is the max file (upload) size? How does this change at various price points?
• Do synched files have to be in a specific parent directory on your computer?
• What type of sharing permissions are available? (view, edit, etc.) Folder level and/or file level?
• What security/encryption options are available? (storage on your computer, in transit and in their data center)
• Do they offer an API? If so, how well documented is it? Are there samples? Is there a developer support community? How are objects references, via pointer to a location or does each have a unique identifier?
• How does sync occur? Is the entire file replaced or are just changes sent?

What do you think? Anything you would change or add?