The Samsung box is behaving correctly. See the diagrams on page 17 of
http://www.dtg.org.uk/publications/books/afd.pdf. The Samsung is behaving as shown in the second line. The older Pace boxes aren't capable of doing this, so have to use the 'best compromise' shown in the first line.
If the programme has true widescreen content, with important stuff going on at the edges of the pictures (usually in a widescreen movie), the Samsung box will use the mode shown in the first line on page 19, and you will get a 16:9 letterbox.