Firstly, my BB3 arrived Thursday and went together very well, all holes lined up and every nut, bolt and screw present and correct. Only two problems encountered though. When I took the MCU out of its bag something fell on to the bench. It was the USB socket, the solder was so dry it had fallen off, easy to refit but indicative of the dreadful quality of solder flow, a bit worrying for the future life exoentancy of these boards. On inspection the others look poorly flowed as well
The second problem was that when powered up with either of the DCP405 modules installed the unit was in a reset loop, unplugging the modules enabled the unit to boot up ok. This was solved with a firmware update from v1.0 to v1.6.1
All working now, very happy and just waiting for the DCM224 hopefully later this month according to Mouser.
Have calibrated it with a newly calibrated DMM6500 and the accuracy and stability of the BB3 is really impressive. So far 10 out of 10, thank you to the developers, a great product. Now to start programming 
With regards to the electronic load you are proposing to design, are you in danger of reinventing the wheel? There are plenty of loads available for very reasonable money already. I have used several different models over the years but this one from Tenma https://uk.farnell.com/tenma/72-13210/dc-electronic-load-prog-30a-120v/dp/2848407 is an amazing unit for around 250 euro. It is spot on accurate and comes as standard with USB and ethernet, from a business point of view could you not just utilise something like this and save a lot of development effort.
In fact spend time producing a 2 and then a 4 quadrant module that interfaces with the Tenma
I already use it with a power supply to make a crude 2 quadrant test bench to run intelligent charger tests.
Thanks again for a great project, Mike
Hi Mike and thanks for the helpful feedback. I don't know if you
followed what we went through in the first production batch of BB3 and, I would say, the criminal actions of the
Bolek & Lolek bros, so it's no wonder that the USB socket fell out. I believe that no other problems will arise and that BB3 will serve you well.
It's strange that the DCP405 r2B11 (green PCB) was causing problems with 1.0, but it's good that it's working with the latest firmware now.
Regarding BB3 programming, I think the real fun is just coming because we are working on
EEZ Flow, I will soon start writing a bit more about this in the
https://www.eevblog.com/forum/testgear/]Test equipment[/url] section of the forum. In the meantime, feel free to install EEZ Studio and maybe play around with examples of MicroPython scripts that can be downloaded to BB3 with few clicks.
Regarding the mentioned electronic load: yes, it will look like a reinvention of the wheel, but the whole BB3 is something like that

. In terms of price, if I manage to make a new module, it will hardly be as attractive as the mentioned TENMA. Such prices are impossible to achieve with production in the EU and with modest batches (100 or less pieces). However, what such a module could offer is convenient integration with other modules with GUI just as in the case of existing modules.
By the way, @wizard69's idea from post #558 isn't bad at all. It should definitely be taken into account.
Yes, a 2- and 4-quadrant DC power module would certainly make more sense, it has been talked about for years. I guess something will happen about that sooner or later.