Your are very right about attorney, but thing is when I 'd consulted with two attorneys about this form, I 've got two opposite recomendations. One recommend to use ETA 750B, another consider it for OR irrelevant. As I understand you are/were applying for EA and NIW, these are kind of different from OR. In INS www said nothing about OR, but required this form for NIW(my guess for EA also).
I have a question, have you submitted evidences in duplicates for your petitions, because if you submitt ETA 750B, you have to include the same evidence as for I-140 form, for example papers, copies of degree etc.
Thank you!