> that strange RFE where they basically just said "send us more info
> about 2 of the following 6 criteria". While we were preparing those,
I guess I was a bit alarmist back then

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> they spontaneously changed the LUD to approval (without RFE answer).
I hope you, your attorney, your employer or you have received a paper copy of the approval. The online system can be wrong.
> When I got home, the FP notice was in the mail - it had been
> issued a week prior to the I140 approval based on the pending 485.
FP notice is independent from I140 processing. It just means the computer got around to issuing it. Some folks get it like 3 months after they filed I485.
> I guess there is no way to predict how long the 485 approval takes
> and thats OK.
You must be catholic or hindu

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> The Univ did petition for meand I plan to be here at least
> 18-24 months more in the same or similar job classification.
> But after that I may have better options elsewhere and thats
> why I was wondering about how to negotiate the change if the 485
> is till pending.
Well, the GC is for future employment, so technically you have to start working for the university AFTER it is approved. But they might ask you for a 'employment verification letter' when your case comes up for I485 approval. They (probably correctly) assume that if you don't work for the employer on day approval -1, it is not likely that you will work for them on approval+1.
If the university sponsored you as a researcher at the 'instructor' level, you should be fine if you stay in an academic position in the same general area of work. If you leave and go into private practice without any academic attachment it could be problematic.
I am not sure whether the AC21 law (free to change jobs within the field 180 days after I140 approval) is applicable to OR petitions, I doubt it.