Have you used Dyalog APL recently? They now have a rank operator and fork/hook from J. I am learning J but haven't made up my mind about this.
I'm aware of the licensing costs, I'm more curious about whether Dyalog is obtaining popularity versus J, and if so, why. Of course, three new people going to the Dyalog conference would be a 10% increase in popularity, it looks like… so maybe this far out on the long tail it doesn't matter.
Being slightly more serious, I do web dev, mostly backend, for a radio astronomy observatory. I don't know anything about the science, but I wind up executing their routines in the cluster and doing typical database apps. I don't have much time on the side but I have been enjoying trying to learn J and realizing how much applied math is missing in my background!
I am one of those who stare at arrays! [1]
[1] http://www.aprogramminglanguage.com/