That is true, you can only save as epub in Sigil. But epub is nothing more than a collection of html files and their associated images all zipped together.
In Sigil if you right click on any of these files you can select open with and open in any other editor you like.
Or you can use a zip program to open the epub and work with the files in any program you like...but you need to make sure they are zipped up in certain order with certain files not zipped...which ones escapes me now. There is a tweak epub program which facilitates this and it is built into calibre.
Sorry to repeat... DiapDealer got in first!
If Sigil makes things too simple, you can stay in code view in Sigil and muck about in the html all you like. For me, I work in both views - code view to tweak and book view to preview. It is easier for me to join broken sentences in book view than code view.
Last edited by mrmikel; 01-20-2013 at 08:20 AM.