Originally posted by ETA-GC
Seems to me that unless you want to leave the position for which the I-140 was done and do a job that is different from the one on the LC (which would require the green card), then there's nothing wrong with having to wait for the I-485.
If your current position is stable, no problem -- you'll eventually get the 485.
If you switch to a more stable / better position (same job description), no problem -- you'll file AC21 and eventually get the 485.
On the other hand, if you don't get the I-140 and you have to wait, say, another 6+ months to get it and the I-485 together, you will be unable to use AC21 and if your company/future position goes under (or the company's financial situation blocks the I-140) then you're out of luck. Kinda like the problem with using Consular Processing I guess...
Note also, that even if you get the green card (I-485 approved), you probably can't leave the sponsoring company for 6-12 months without risking the USCIS interpreting this as fraud.
ETA