I actually came here to comment on the blur on the edges of the large drops. My guess was it was a fast way to give a passable result for the more complicated refractions occurring at the edge of the drop. Is there a link at which I can follow your work? Thanks!
By that point I had already spent more time on this than I'd have liked, and allowing for a little blur was an easier way for it to look good enough.
I haven't been doing any "public" work lately, but I'll post anything I make on my Twitter[1], especially if I ever get to finish this updated version.
But there are some neat tricks which, while not necessarily transferable themselves, might serve as inspiration for other problems.