I just did a quick test with the 6-book bundle I split a few days ago. It seems to create clean and tidy epubs
I did notice one thing, though... the opf and ncx files had both had all their end-of-line characters removed after the split, which made them difficult to read. Was this deliberate?
Hopefully, I'll have more time tomorrow to test a few more bundles.
Thank you for your hard work