In the AC21 memo (
http://www.shusterman.com/pdf/ac21-51205.pdf), Answer to question 5 (regarding wage difference) states that "A difference in the wage offered on the approved labor certification, intital I-140 and the new employment cannot be used as a basis of a denial. However, a substantial discrepancy between the previous and new wage may be taken into consideration as a factor in determining if the new employment is "same or similar" "
Considering that the labor has been filed 4-5 years back and "same or similar" jobs in today's market might even have a 100% or more increase in salary as stated on the labor certification. The AC21 memo does not state any preset limits for wage hikes; which makes it difficult to decide.
Any comments from Ginnu and other experts are appreciated.