Simultaneously moving both handles on nodes.
Is it already possible in Gimp to select both handles and move them together to form symmetrical outlines?
Or can a path script be written to accomplish this?

I don't know about both handles of an anchor, but you can drag the front handle of one anchor with the back handle of the next one, by simply clicking on the path between the anchors and dragging it.

YES! I found that if you click shift while clicking the path in between the node handles you want to move you get the effect i need.Moving both handles on both sides of the path at once for perfect symmetry.Awesome!

I should also add you need to be in design mode in path options for it to work.
Thanks dd.