This is all fine and good until your internal user needs to involve the IT department to open the firewall to your SaaS service. You'd be amazed by how many Fortune 500 companies block things like Evernote and DropBox, Google Docs, etc...
At which point, the purchasees will be going through some official channels to get at your service...
At which point, the purchasees will be going through some official channels to get at your service...