I finally got around to installing a private instance of PhpGedView 4.2.4 for testing. Usage is definitely not intuitive, but I got going by reading a little of the manual. While the learning curve is not huge, it will prevent most members of my family from getting started without significant hand-holding.
As the name implies, PhpGedView uses GEDCOM files and in fact you must have one in order for the system function correctly. Fortunately, PhpGedView can create one for you if you are just starting out, but this step was not obvious without reading the manual. This process creates an initial, nameless, individual which I struggled to modify initially before getting it to work.
PhpGedView uses a RDBMS for main storage and only updates the GEDCOM file automatically for certain trusted users. An administrator must accept and push the changes of other users. The administrator can also import and export the file easily, which allows the database to be maintained in a completely separate application.
However, despite these annoyances, PhpGedView is quite usable and satisfies my immediate requirement of having a common place to record the family history, which is haphazardly written on bits of paper scatted across different continents now. More importantly, the fact that the data is portable means we are not locked into PhpGedView if we find something better in the future.