I've not found a problem on my Sony if the ePub looks good with ADE 1.7.2. I keep that old version around for testing. I've also used Bluefire Reader (uses ADE) for the iPad and iOS without a problem.
Do you actually have a proper ToC in the ncx file or are you just doing it via a list of links?
As for Sigil being WYSIWYG, it's not fully so. Also, Sigil has issues sometimes with the display of the ePub due to QT that it uses to render the ePub. That's why you need ADE on your computer to check the ePub.