I export my settings in Visual Studio and if I ever move to a new machine or have problems, I use those backed up settings to restore Visual Studio to the way I like it. It also
For the benefit of others, as you mentioned this feature doesn't seem to be supported across versions of Visual Studio, presumably because of a change in the DTD/XSD for the settings file? At any rate, here's where the settings for your custom toolbars lie in the "Import and Export Settings..." dialog:
Note: Your options may look different, depending on the settings you exported.