I wrote to Laura, and she graciously reviewed my results. She attributed the standard error discrepancies to a change in IRT score variances. Specifically, the ECLS-K math and reading scores have been re-scaled since the original data set was published, resulting in larger variances in the currently published version. She supplied me with her version of the original public-use data set.
The updated results with the original data set are nearly identical to her published results. I feel confident now about using ECLS-B jackknife replicate weights for SEM in , and I learned a lot from attempting the replication.