I don't currently run a business but may someday so have an interest in seeing this problem solved, and in fact I was thinking about it recently.
Would it be feasible to write a nice front end, probably with PySide and QML or something similar, to the likes of SMBLedger or ApacheOFB? It could come as close as possible to the Quickbooks interface and only provide the functionality needed by small businesses. A script could be provided to set up any necessary server software.
If so, for anyone who has compared these backends, which one would be the best starting point? I may take a look at them myself...