I like my action at 1mm on the G. Increasing to 1.5mm on the E. and I like my neck absolutely flat, no relief at all.
I've been told that my demands/preferences are... well, ridiculous. I don't think so though.
If that's 1mm measured from top of fret to bottom of string, with the string unfretted anywhere I'd say that's extremely low. The string needs space to vibrate in when plucked and at that height i'd expect to get fret buzz almost anytime the string is plucked. Then again, this may be the sound you're after.
I think for some, obsessing over an utra low action seems to be an alternative to actually playing the darn thing! Not saying this is true in your case, is just an observation IME
