Just my thoughts:
I don't remember battery support was mentioned earlier. It's unique, but very specific. I would have no use for it, and rather power it via a plug pack only. Doesn't matter, it's Dave's power supply
I would have used a DC-DC converter with wider input range, though. Maybe even buck-boost so really low voltage applications can be powered effieciently.
Oh by the way, a high frequency regulator is by essence not more efficient. There is a trade off between that as higher frequency equals in more switching losses. Take a look at the datasheet of LT3505, it clearly says that the programmable frequency set should be used so the power supply can be very efficient or very small (in PCB dimensions).
Also, you mentoined in the video that the tracking regulator will be +2V of the output voltage. What happens in a long period short circuit operation? All the output power would go into the LT3080, which would be dissapating 12W (12V 1A) or more.. maybe make it so that it follows the live output voltage instead (or only if the output voltage deviates alot from the input).
I wonder how stable the power supply is with a constantly adjusting input voltage on the LT3080. I also wonder if the update speed is good enough , because now all is being controlled through I2C.
I like I2C for it's bus capability, but it's so slow. C'mon 400kHz, you can't even get 30kB/s over that. Whatever, it saves a ton of I/O space and makes the design simpler.
I see you also power the whole system with a LDO. How much would the screen+backlight+control circuitry draw? If it's like 100mA, you're probably dissipating 5V*100mA=500mW in the LDO there..
I really like the new INA209 chip. I think it's a great choice over the microcurrent. Also measuring high-side current is so much better than putting a 1 ohm resistance in series. It also makes the power supply stable for applications with low-current sleep but high current bursts when operational (like sensor terminals sending data over GSM network).
The LM358 opamp is not rail-to-rail btw, you have to pick one which is.
I also have concerns regarding the maximum output voltage of a typical R-R opamp, as it sometimes is 10mV or even more under V+, which means that opamp is constantly reading 10mA current draw, on top of the input offset voltage!
I find it disappointing to see the 'ultra high resolution' thing removed though. I really was looking forward to modding or expanding the PSU design with an even more precise measurement capability (as I have a design back from project that had 16-bit resolution auto-ranging from several mA up to 2Amps). But I guess that would be my own spin-off, as I hate Arduino and still don't understand you're putting up with after all the trouble you've had with it
The ethernet control thing is cool feature tho, especially an expansion board is a great idea to integrate.
Going for complete SMD kinda spoils the fun as it's not a kit anymore in sense you'd have to solder the PCB, but I guess you're right for being able to pick so much more and better components.