Hi Eric,
Thanks for using Syncfusion products.
We have analyzed the reported scenario at our end. The data for the grid can be loaded through PopulateValues() method or QueryCellEvent event based on requirement. However, the GridControl does not have any API support to differentiate the virtual mode of the grid since, the both options populate the data as CellValue. So, we deeply regret to let you know that the Virtual mode of grid could not be determined, and we would suggest you to, use an external property to determine the virtual mode at your end.
Please let us know, if you have any concerns.
Regards,
Arulpriya