While I’m here, the fact that when you line the Pixelblaze and expansion board up against each other on a piece of protoboard so the gnd/dat/clk/5V pins are on the same rails, the boards themselves are misaligned (despite being the same width) makes my teeth itch.
I’m sure there are reasons for the above but I was really thinking I was doing something wrong there for a bit.
I don’t think you are doing anything wrong, they just weren’t designed with this as a goal. The expander has been revised a few times and something probably got nudged along the way.
Feature request for next hardware spin then: make them line up on a breadboard-compatible grid. Pixelblaxe and friends are expensive so I want to “socket” them into the various iterations of my main controller board (which will eventually have power management and other stuff on it.) Making that easier helps a lot.