Hello…
Is it better to works at real scale with vray… or it doesn’t matter ??
i think i remember somewhere that there was a glitch with it and vray
I do most of my stuff at real-world scale(1:1), its ok for small scenes but large ones you get the dreaded “Scene bounding box is too large, possible raycast errors” so you’d need to re-scale.
It’s a matter of choosing your system and display units carefully.
Best regards,
Vlado
Hehe! i think i didn’t explain myself to well 
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I generally work 1:1 this being 1 unit = 1mm (old habits!) which is ok for small scenes, but i find with large scenes i get the “bounding box to large” error. So i re-scale to 1unit =1cm or 1m..
Thanks for your quick answer…
I work 1 unit = 1 cm…
this is an old neverending issue…
working as an italian architect I can say that we actually use cm (system unit) for our projects but from when I heard from Vlado that Vraylights work in meters I tried switching to meters too (system units); I think of display units only as a tool to avoid not useful decimal numbers in our spinners.
I prefer leaving mm for mechanical drawings but I can remember someone using that units saying that it allow more precision in their settings; I don’t know if this make sense or is a sort of “urban legend” 
maybe another clearification from chaos could be useful
my 2 cents
a.
Actualy, I’m interested in knowing how display units would affect vray in any way.
System units I get, but aren’t display units just an UI thing to make things easier when working?