My question would be what is the advertised accuracy and repeatability of either unit.
IMO your in no mans land and normal DIY guys do not own any test equipment that can detect that small of a range accurately.
Chinese shunts are often based on 75 mV drop at max current. Vitron are usually 50 mV drop at max current.
I would not put much expectation on accuracy of a BMS current readout with multiple chip resistor current shunts on BMS PCB. Even if individually calibrated they have terrible temp coefficients and baked by series MOSFET heating.
Some really cheap BMS's just measure voltage drop across series MOSFET's for their current measurement and throw in a fudge factor for MOSFET Rds_ON shift with temperature.
My question would be what is the advertised accuracy and repeatability of either unit.
IMO your in no mans land and normal DIY guys do not own any test equipment that can detect that small of a range accurately.