1) When we got the power bus set up, we tested the regulator output at each point, and to our puzzlement, we were getting -5v, not +5v. WTF? K & I couldn’t figure it out, so we went over to Noisebridge (we were working only a few blocks away). We showed our power bus to Mitch, and he spotted the problem in about 30s:

Yep: Adafruit’s power connectors reverse the meaning of the gray stripe on the wire. We’d been using gray=GND, but now we have to watch the actual progress of the wires. It’s a PITA but workable. We cut them all out, restripped, resoldered, re-heat-shrunk. Fixed.

2) As we went through all the strands, we found that one of them has two plug ends, rather than one plug and one receptacle. No big deal, I can gender-bend with a connecting cable.

3) Finally, and most problematically, one of the strands has what seems to be a bad pixel. Note that on each color shift, it flickers uncontrollably.

I’m hoping Adafruit will exchange the flickering strand, and with luck, the second slightly flickering one. Will keep you posted.

Edit 1 July: Adafruit is sending me a replacement strand, and letting me keep the defective one to be cut up into parts at some future time. It’s been a pleasure doing business with them.