As for using UniFi Protect for contact, leak, and motion sensors, I am very happy with the outcome. Coupled with all new switches, I have no complaints (other than the memory leak, lol). I would say the motions are a bit finicky for locations, more so than my old sensors, it’s how they’re designed.
Whether it’s mesh strength, types of devices, number of devices, quality of devices, etc, we all get and see different versions of HE. I see people talk about their 5 switches spread around the house in a mesh configuration, or not having repeaters for battery powered devices, etc, as if any hub can fix a lack of understanding. You never know who you’re talking to or their skill level. Although one can draw conclusions.
My level of commitment and my means to do so, may not be typical, but it works well for me and my family (kids are grown, so mostly my wife and pups).
Back on topic - the sensors work great, but you need to plan appropriately. Good luck to anyone heading down this path. Take care!