Professional DMMs are nice because they've thought through all the failure cases. This meter is nice, but the relay on the current range select (K2) is set up

Professional DMMs are nice because they've thought through all the failure cases. This meter is nice, but the relay on the current range select (K2) is set up so that there will be a break in the current when it switches ranges. On inductive loads, this would cause arcing and can damage the relay. It could also shoot through D6 into the voltage rail, potentially frying the meter. On digital loads, this blip in power might be enough to reset the circuit you're trying to measure. A better way to put the relay is to always have the 10 ohm resistor in series, and switch in the 1 ohm in parallel when needed. Of course the resistance will now be 0.909 ohms instead instead of 1, but that can be calibrated for in software.