I have a 2006 GT and found the ORIGINAL saddle very hard and so I purchased a Sargent front seat and a Sargent cover for my pillion (they we're manufacturing the pillion seat at the time). I did a couple of 2K tours on the Sargent and found it better than the BMW original but not fantastic. The riders seat seems to be broader than the stock and better padded but still induced a numb bum between fillups.
When BMW here in the UK announced that they would swap the original seats for the new "improved" seats I joined the queue and eventually got the replacements for rider and pillion.
I now use these all the time and the Sargent is confined to my garage gathering dust as the newer BMW seats seem to suit me better.
Still it's a nice option to have - but expensive!