I am a great IQ fan, but have given up on this one. Far too convoluted for me (although convoluted is usually a good thing!).
I'm sure Nimrod has done a spanking good job, but it seems cobbled together to mark this occasion, with little thought for us, the poor solver!
This may be sour grapes, of course, having come up short as a solver!
Once I start hanging around here for hints on a regular basis, I know it's beyond me, and my self imposed rules of not cheating "too" much must be obeyed.
Little bit of a missed opportunity to draw in the new "I" solvers, also IMO.
Good luck to all!