Mmmh! I dropped fast The Ambassadors in the feedbook version to take up yours. I was a little worried about the bulk, so switched all the pieces I had to my Archive Calibre library (which already contained the illustrated Tour in France), but that was unnecessary: it reads on my more than half full PRS-T1 like any 300 kb small epub. So I'll drop the pieces from the Archive too.
One thing I appreciate in your productions is the margins - I hate those thin margins where the shadow of the borders, though narrow on the PRS-T1, encroach on the text.