While I was sanity checking the flash timing, I figured I should make sure the light estimates were roughly in-line, too. I used the second prototype with a "5W" green LED (4 30x30 mil chips). The power supply I had on that bench limited me to 10V, so I could only run the LED with 4.4A pulses. Here's an exposure from a single 1.08 us flash from the LED:
Sure, it's grainy, and could use a lot more light over a bigger area, but that's with a single $1.23 LED. It's also less than half the brightness I had achieved before with a 24V supply. According to my photodiode sensor, the 24V pulse was 2.23x as bright. I'll have to drag the other supply over there and test it out.
I'm going to call it a success. There's plenty of room for improvement, but it's encouraging.