I filed I-140 being on O-1 in April 2002. It is generally not recommended to press on "outstanding visa status" in your petition, as they say it has different requirements from EB1-A. I did incorporate some of O-1 visa qualifications (like performing in critical capacity) in the letters from my supervisor and NIH administrator.
I did not extend O-1 visa after I filed I-485.
I got my I-140 approved after RFE last November. Many people were approved before me with a later mailing date. But as of today, at least two I-140 petitions are still pending since April 24, 2002, that have eac# very close to mine. It is impossible to say if they are EB1A or NIW.
Conclusion: nothing does metter - Visa status, family situation, qualifications, etc. Simply random processing.