Ok so I have the following to report:
Hobby king sucks balls
I ordered 5 medics from them last week, looking through the backs 4 had yellow boards and one had green.
The green one was at worst 10mv off from another known good medic, a cell log and a multimeter (which all read much the same)
The green one had very few smd resistors on the back (shown below) The yellow one had many more in a row and seemed to be the same design as the reds
All the yellow board ones are crap. Some cells are spot on, some 20mv out (which I'd be happy with) but all of them have 1-2 cells that read 40-50mv low. This is pretty crap when I had a perfectly balanced pack with all cells being 4.16v and 2 of them read 4.11
Also worth noting is that the green board which was accurate used a central "blob" chip while the others (including an accurate red one I got from the ebay seller methods linked earlier) all used normal surface mount chips and actually seemed to have more other components too (hard to photograph without pulling apart and I only used my phone but you get the drift)
First pic - 2 boards from hobby king. Green one is good, yellow one is bad (green one has QC sticker on it so maybe that's why!
The 2 red boards are from the ebay seller methods linked. One is accurate one was DOA and doesn't power up.
Conclusion: Roll the f*%#ing dice!
The second pic shows the internal components as mentioned above.