Great tip!  Works well.

Hello Steve,
Currently you can't use formatting on the Value field. You should pass the format expression in the Label field and use <label> for your Data Label -> Format field.

With the next service pack of the Vision for SharePoint we will allow formatting of the Value through the Data Label Format Strings.

Best Regards,
Nevron Support Team

I am unable to pass formatted Values to the <value> option in Data Labels.  See attached Data Grouping format syntax and Pie Chart.