Can either of you much more deeply elaborate on exactly what use case you are trying to address? I could take a guess at maybe part of what you're trying to do, but a more elaborate explanation of what you're looking for might yield you better guidance or ideas.
One example: I have temperature sensors inside my fridge og freezer. If temperature rises above some given thresholds, I want to be notified because that means someone forgot to close the door, or power is lost. But for this to work I need to know that temperature readings is no older than x minutes. If readings get to old, I want to be notified.
When I get up in the morning and look at my dashboard to check outside temperatures - I want to know that what it reads is the current temperature outside (and not yesterdays last reading if sensor battery happened to die, or there could be other reasons for 433Mhz sensors not to be caught by Rfxcom). So I want next to the temperature some text in smaller fonts that says "last update at %date" .
Domoticz, Switchking and other HA-gateways provide this out of the box. Also, "lastchanged" on devices and sensors are available when creating scripts.
If lastupdate is available in the PLEG-plugin, that is good if the lastupdate value can be used in scripts. Still, I want the lastupdate value to be displayed on all sensors on tablets and mobile apps.
