Duckduckgo has a shopping tab too (although, it's not as functional and comprehensive as googles, in my experience). If there's adoption of the schemas, I'd guess all the shopling crawler sites will use the data.

If you expect to show up generally favorably in a shopping comparison, having shipping data available would seem to be useful, since people may not want to purchase without an idea of when they'd get the items.

Of course, if you don't get purchases through those channels now, adding shipping data probably won't help.