Several folks commented they dug it including the cook in the toasted cheese grill truck (which was delicious). One guy even told me about how he used to program a PDP-8 minicomputer back in the day!
While hard to see in daylight, the LED segments are quite visible indoors and, thankfully, most of the faire was inside. The common anode of each 7-segment display is driven directly from a separate PWM pin on the 3.3V Arduino Pro Mini. Here's a quick diagram made in Fritzing:
The 7-segment datasheet lists the min Vf as 3.2V and max Vf as 3.4V. Each display's LEDs are not getting as much voltage as recommenced after the drop from the current limiting resistor connected to the common anode. I could have powered the displays via the 3.7V LiPo battery voltage and used the Arduino pins to control transistors. However, I decided against finding space for 4 transistors and went with the direct approach (after measuring the current consumption is below the Arduino per pin max).