The RadClientDataSource is a wonderful control to greatly simplify binding controls to data for client side operations.
I'm finding though that I don't have many scenario's where I can get the data in one swoop. An example is an event log viewer with 100000 logs that I don't want to transfer to the client in one transfer. Rather, with a custom date range that can be set via date pickers, I'd like to be able to tell the data source to go back and get fresh data for the new filter parameters.
Other scenario's can be for contributions where in our app, people are part of teams and they can be part of multiple teams. Upon switching contexts, from one team to another, the data needs to be refreshed because there's many thousands of records so I cannot load everything at once on the first go, besides, that kills the network pipeline.
I guess what I'm getting at is that I find there is the need to have the ability to filter the data by passing parameters from controls on the client to filter data returned from a stored procedure expecting said parameters. It's really the only way to go when you have screens that are generic that deal with large datasets because any alternative will kill performance.