A few things:

First, harvesting lettuce in a container shoulder high and 3 feet deep is a giant pain in the butt.
Second, the lettuce doesn't appear to be all that disturbed by being crowded.  (but it does make harvesting a little more difficult)
Third, I'm really hoping it works well to grow the plants in the pond baskets full of gravel - it will be so much easier in many ways. (I planted some fresh seeds in them today)
Fourth, I tasted the lettuce and it seems just fine to me.
Fifth, the lettuce on the back side, closest to the exterior window, is definitely bigger than the rest.  Clearly natural light is a hot commodity.
Sixth, I'm thinking about getting some more goldfish and putting them in the top chamber to see how they do.  We'll see.
Seventh, the lettuce is picked and washed and bagged up for testing tomorrow.  I will provide a full report.