Mats PT 1 goes into quite clear details on all the requirements for passing and updating RVR/IRVR, including not indicating it better than reported, turning the lights down and all that jazz. Oh and reporting IRVR Won't necessarily mean you are in LVPs either.
For info the IRVR on the ATIS/METAR is in general a 10 minute average at the time the report was made so could be a 10 minute averge that's now 29min out of date. Dependant on SPECI updates but again you'd only here them on ATIS.
The live IRVR is again in general(does vary with type - a one minute average.
Key point was made by a pilot - they all just a magic number related to some other magic number for some policy - that someone one day might just change like getting rid of LVPs for low cloud, key thing is what the aircraft pilot doing - you could say it's raining lemons, by that point ruling factor(dependant on a/c minima) is do we see the lights/runway before we hit our other magic number someone made up.
What you report doesn't cause crashes it's what the weather actually is at that spot in space and at that moment in time!