I got one board tried it out and have just gotten two more.
The boards arrived in a outer opaque bag, bubble wrap, and then a heat sealed anti-static bag, all placed in a amazon box.
I decided to fool around with the boards, the display loses accuracy below 5.2Vin I expect that it has a 5Vref that follows the Vin down, It was still outputting 15V with a 2.5Vin as measured with my voltmeter the display reported more as it looked like its Vref was too low, and the display dims quickly as Vin goes down.
I pulled 3A into the 10A shunt setting on my meter, it stayed fairly constant on my meter, the display bounced a bit and the heat sink got warm after a few minutes.
The input and output voltages agreed quite closely with my voltmeter, the output current seemed correct also.
It seems that only the output current is displayed whether Vin or Vout is displayed.
The input reverse polarity protection seems to work fine, I hooked it up backwards, it just sat there with nothing happening, and worked again when connected properly. I very useful feature for beginners, convenient for the experienced.
The Vin range is wide enough to work with lead acid batteries from 6V to 24V nominal it might display inaccurately on a 6V battery near end of discharge ~5.25V depending on whose chart you use, but can also work at 24V while charging at ~29V without being outside spec.

Thoughts on possible upgrades:
1) make the higher power version buck/boost also it would be nice to have 12A available, if they had been I would have ordered some already.
2) move the minimum Vin down so it could be used with a single Lithium cell, it should work, but does not display correctly
3) a way to turn off the display either via button or even a jumper, the display is nice, the display is bright, but sometimes it would be better without the display on (or the LEDs for that matter), I have seen it glowing at night from across the room. Tech Tango also commented it would be nice to turn off the display, even a pair of holes for a 0.1" header with a bridge that could have the bridge cut and a jumper or switch installed would work.
4) A version with a higher max Vin could also be of use, e.g. 60Vin-max would cover 48V nominal lead acid system while charging at ~58V
5) Similarly a higher Vout-max could also be of use for pretty much the same 48V use case, 48V systems are fairly common in telecommunications and I bump into them.
6) I would be nice to have the schematic/design available to reference so I would know that "Oh it already can do 48Vin the parts are rated well above that" rather than "Hey I hooked it up and it worked without blowing up..."

All in all I have been very happy with my units.
Enough that I have ordered more...
I hope you find them useful them too.

The buck-boost works great, BUT the voltage overshoots when powering on by 30-50% (verified with oscope) if attached to no or small load. It is not soft start! This occurs whether being plugged in initially or being switched to the "on" state. I believe it destroyed one sensitive component with this overshoot.
That said, I have bought 2 :) Great product for the price, IF you know not to connect sensitive electronics without a substantial decoupling capacitor.

Built up a small 20 watt folding solar panel setup to run small electronics in the field. I used this instead of a solar charge regulator and it works just great at converting the 18-24 volt raw solar panel input into clean, consistent lower voltage. I have it set at 12.6 which is the perfect float voltage for my Li-Ion battery pack.

It's really easy to install and used I'm going to used it to charge lithium batteries in my case.

I used this to charge a device I lost the charger for and used the DC input from a charger I didn't need anymore. Well documented.