It is a easy thing to test out:
I would say the model is not 100% right, but close enough to see the point. The video is sped up obviously, but I saw quite an improvement in intensity of caustics with version 10.
As romullus said, wouldn't mind inaccuracy too much If it was in exchange with that speed. If it was possible to use GPU for anything, it would help a lot, even if it meant as a separate Render Element. We could merge those in postproduction.
I also tried to add a plane with displacement above this to simulate water with caustics falling in, but this was the result:
You should just about see where the outline of the object is, don't know If this is how it should be working.