I've been happy with this unit for thousands of miles. I get a false alarm every once in a while but no big deal.
If you want to, you can use an old non-sim card phone as a monitor instead of your working phone. All it needs is the app and working Bluetooth.
I bought the booster but don't need it. It's mounted in the driver's side battery compartment and I just clipped it to the battery terminals. If I decided I really needed it I'd try to figure out how to connect it's to switched power. But when I've used it, I just reach in and unclip it.