This tool is super quick for many basic circuit problem. The long lead is handy to get you to the back of the car so every volt-drop test you do is referenced from the battery. The auxiliary negative wire has a female banana jack so if its time to break out a scope just plug in to that for a battery referenced ground anywhere. The high and low tones are great for cramped areas or wiggle testing harness or circuit activation where the screen can't be seen. The voltmeter has min max readings that are fast enough to display network peak voltages for quick dirty go-no-go testing (bus activity VS shorted high or low). Fuel injector test is quick for basic no starts.
The tool often gets a bad rap for burning up modules, It is not the tool but the technician that is the cause. The power supply switch is often just way to convenient so techs send current where it doesn't belong. This is no more dangerous than a fused jumper wire. Experienced techs have little use for the power switch.
With that said I find the power switch handy during fuse testing. When coming across a blown fuse of a rating similar to the PP4 circuit breaker I will power up the circuit to see if the circuit breaker trips (active short) before finding a new fuse. It's also useful for open circuit load testing with a headlamp bulb. I keep the PP4 in a tool bag with my Vantage pro and many different leads and probes. With those two working together you can quickly knock out most most electrical problems extremely fast.
If you have trouble with the tool you will not be disappointed by the customer service. They are exceptional!