I remember seeing this a few years ago and dismissing it as being too expensive (2-4x memory use, and larger filters required)... but my current project has a lot of layers of translucency, and GPUs can now deal with the bandwidth requirements for this... so I might give it a go and see how it looks
I don't think it looks that good to be honest because it is not close enough to how real caustics behave.
It doesn't model caustics at all, so anything that looks like caustics is just an artefact of the filtering
Ordinary shadow maps are an apples-and-oranges comparison, because they don't support translucency at all.