As a referral for NetSuite I would say that one of the questions I am asked most often has to do with backing up the data.  If you are used to having your data where you can see it, touch it, hold it, then NetSuite or Saas as a whole is going to be a huge change.  And, if you are used to being "tied" to your office because that is where your data is, that too will be a huge change.