Hi David,
I guess, I never took the time to revisit the thead you referred to. Guilty!
I am attaching a solution file, with a very simplified Export to excel, using the FeatureDataGrid sample from the Gallery.
It covers exporting all the features in the grid (FeatureLayer), the selected graphics, and exporting all the graphics but only a few of the attributes with their aliases.
Please, don't be confused by the name of the solution, I just used an old project to test the export to Excel.
Please, fix the ESRI assembly references. I had to remove them from the bin, because the zip was too big.
There is a line of code in App.xaml.cs, which you should include in your project if you don't want your app to crash if user tries to save over an open Excel file. And you can find your own solution for this, if you don't like mine (I don't like it either, but I am solving problems one by one, so some have to wait. 🙂 )
Good luck!
Let me know if something is not working for you. Hope, we will be able to resolve it.
Darina