Originally Posted by HomelessBook
I didn't say Sigil is not good IF YOU ARE A PROFESSIONAL. But if you have not experience in eBook production, then relying on an automatic converter is useless and will only result in a rough conversion. Then, if you are a professional, bravo! I have asked ePubmatic staff and they too use sigil for some jobs, but they (as you) know how to use it!!! The guy who started this thread is not in your situation, that's why he was seeking help. And if you have not experience, it's better relying on a service provider than on a automatic converter whose output you are not able to edit.
You know that sigil is a WYSIWYG / code editor not an automatic converter right?
Also Baen Books use calibre for, at least, the initial conversion to epub (have a look at the css), I'm not saying they don't give the epub a one over afterwards but that is a decent sized publisher.
Automatic conversions output mostly depend on how clean your original source is (as anyone who ever used the smashwords meatgrinder can attest).