RFE's are issued for cases where they are discrepencies, they usually fall under 5 categories
1. name rfe
2. marriage certificate rfe
3. employment rfe
4. FP rfe
5. birth certificate rfe
so whetehr eb1/2/3 does not matter. But you have a point in that eb3 cases are getting delayed no end, and usually the officer is extra creful and reviews your Labor certification over andf over again before giving the gc approval. this is ebcause, according to the INS, eb3 is the lease priority category and with the slowdown in the economy they are more such american citizens who have similar skills of those with eb3..may not be logical but that is what the impression that is carried.