I've tried Inside Iso a number of times in some competitive PL games a season or two back. I have a few guards who all have good IS, and my intent was to see if they'd get a large number of IS opportunities. Sadly, they didn't. There were some IS attempts, but there were a lot of 3FG attempts. In those games I typically didn't have a great C or PF, so perhaps the GE wasn't quite sure what to do.
I've found more guard IS attempts when I've played LP.