When you set the grid's LoadStyle to LoadOnDemand, the grid will only ask for rows as needed. So the grid will "work" with any data source. But most data sources, like a DataTable, load all of their data up front, which defeats much of the benefit you would get from loading the grid on demand. You will save a little bit of memory, since the grid won't create all of the rows up front, but all of the data rows will still exist. 

So you are essentially correct, although you could write your own data source that loads it's data on demand and that would also work.