is rated for shade but pops in Sun
aachenelf has a thread in which he is impressed with his shade plant Aruncus doing so well in lots of sun.
Maybe we could compile a list of such plants.
For example I was over at relative's home a couple of weeks back and their patch of Bergenia was huge. In the full sun location it was almost unrecognizable (due to it vigour) as compared to my much smaller much less impressive stand located in shade.
I have found similarly for Thalictrum "Splendide"...beautiful in dappled sun/shade but awesome in full sun.