So let's say you live in an isolated location, leave the house to go out to a garage or walk the dog, how useful is a PERS pendant or watch? I am not impressed with how forthcoming PERS vendors are with little details like how far from the base station the wearer can travel. Here's the big player, Philips Lifeline: "Works from anywhere in or around the home, including basement, garage and yard. [Note: Range may vary due to construction of your home and distance from the Lifeline Telephone or Basic Unit.]." So what is that range, anyway? Not stated.
So let's talk about Life Alert -- at 150 feet, you may or may not be able to hear the operator when you press the button, and the button (this revealed by calling the company) works up to 150 feet away. Hmm. Not great if you walk the dog or walk to the corner of a one-acre lot. Visonic's Amber (sold through many resellers, including SmartHome owner's manual of the product, refers to it as 'some distance'. So what if you walk around an independent or assisted living campus and get out to edge of the parking lot?
So let's compare that to a cell phone that enables you to call for help on the phone -- or with a tracking service -- be located by others if disoriented or confused, and with phone navigation for driving or walking to the store. This is the right device to take out of the house -- agreed?