They are quite small. I measured the display area at ~1.0"W x 0.5" high so ~1.118" diagonal. I have read posts from some who feel that the displays are pointless, at least on a CPU block. For devices like the D5 Next and LKS that may get powered up for loop testing while the main system is not powered, the displays are more useful since they allow the user to configure the device locally while AQS is offline, I don't know what the resolution of the Aquacomputer display is but something like
THIS little guy is about the same size. Its resolution is 135x240 and it costs a whopping $3.27 USD. It uses 4-wire serial SPI which may or may not be what the current displays use.
I agree that if anything should get a bigger, higher resolution color display, its the Vision. There have been several posts on the German thread asking about this. The coolest, and most ridiculous CPU block display I have seen is the
Barrowch FBLTHD series. They are 2.9" (diagonal ?), 1440x1440, with an HDMI input. You can even display the Windows desktop on it (which is cool but ridiculous).
Barrowch CPU Block Display w Windows Desktop.jpg