Yes the 900 does have full justification of ePub and no page numbers in the margin. Surely Sony will have enough sense to make any new readers with the updated ADE of the 900.

I like ePub better than LRF because they tend to be smaller files and run faster and smoother in the Sony readers. LRF can get pretty big especially if they have embedded fonts.

You can very easily strip the DRM from Sony ePubs and use calibre to set the font families and font sizes. It does require a bit of hacking but it is reasonably easy.

You can rename an ePub if it is not DRMed to a *.zip, unzip it, use your favorite HTML and CSS editor to make changes, then rezip it. Calibre can then convert it back to an ePub (renaming *.zip to *.epub doesn't always work with Sony readers).

Epubs are also going to be much more portable to other devices than LRFs.