Glen, I don't have the answer to your question, but I just wanted to chime in and say that multiple-hour imports are something that we have come to expect with large EAD or CSV files. How big are the EAD files? We have experienced this with EAD and with CSV files with tens of thousands of file-level descriptions.
Our experience with import has been that the indexing doesn't really add a huge amount of time to the import and leaving the indexing turned on can save time because you don't have to rebuild the index after the imports (which also takes hours). We've also found that it is best to import large files in small batches, even one at a time, rather than try to do one import:bulk command that might fail at some point along the way.
I'd be interested to hear if you can run two or more bulk uploads at the same time, but I hope this helps!
Cheers,
Creighton