Excellent idea, and I've given it a try.

I have a Sony 505, and tried importing an html file with justified text. Appears as justified in Sigil, so save as epub, but when I view it on the Reader it is not justified. Is this Sigil or the Reader?

The reader.

There are rumours of a firmware update to fix this, but it is just rumours at the moment. Many people would be happy to have this fixed.