Some places to start for a quick review of some of the relevant issues:
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The presence sensor fob is a zigbee fob–it should have a maximum range of 100 feet, usually more like 50. Range is not adjustable for this device.
The phone based presence is different technology–it has a minimum range of 250 feet and may indicate much farther. Range is adjustable outward from the minimum.
As for status…everything should update eventually, but both zigbee and zwave are mesh technologies and on top of that there is a Lutron patent issue specific to lights.
So for checking when you’re on vacation, no problem-- within 15 minutes, statuses should be updated. but it’s not like a star topology like WiFi: you don’t have constant real time monitoring of each device. It’s more of a sampling model, which means individual devices can be cheaper in both energy and money. That’s not a SmartThings issue, it’s true for any zwave or zigbee mesh install.