回複：How difficult is Eb1-b, compared to Eb1-a and NIW?

Four letters seemed to be not enough for EB1B if they were written by famous people. However, if you have very strong background, and you have included other evidence such as awards, publications, reviewers and media reports about you, you may be OK. Otherwise, a RFE is very likely. EB1B is easier than EB1A, but is more difficult than NIW.

In fact, there is no need to rush for EB1. I believe visa number will become available in October or sometime later. For NIW, it is easier but there are a long list. It is expected that cutoff day will be back to 2005.

Good luck!