This method allows you to add/insert/update (even with Xceed's grid) quite easily, but does not save implicitly, ie. you have to manage it yourself.
If you prefer to batch up all your changes and save en mass at a special point (this is a common UI pattern) - then this might be a great solution for you.
One issue with with approach however, is that it only supports the whole table, ie. not based on queries. This might be fine if you are using the WPF's data filters, but it's not an optimal result with large amounts of data.
I'm planning to investigate these two aspects in the near future, and hopefully I'll find an elegant solution.