Just found an amazing discussion of the merits of the Softbook 250e and its successors, the REB1200 and REB1100.
The translated posting for those that don't read russian is
here.
Has some nice pictures on the first page showing that the Softbook is a bit bigger and heavier. You win some ("bigger"), you lose some ("heavier").
p.s. the original russian posting may be found at
http://www.the-ebook.org/forum/viewtopic.php?t=4492