I've only checked out the joomla jb, so i can only assume that the others are like it.
Without the ability to upload existing data, their value is limited. I realize that i should buy the license for full access, then i can do what i want. but i'm not inclined to do that without the ability to test the install before hand. currently all i can see is "it appears to work"
letting free users upload a limited (5mb) database would give enuf for people to see how clean and speedy the installs are without giving up enuf to allow webmasters to migrate an entire userbase.