I suppose the next question is: Is the $3K bump to a F800GS worth it, or is a Sertao with $3K worth of kit a better value?
I vote for $3K worth of extra kit. Personally I don't need the extra power of the 800 and I like using regular gas in my 07.
On a recent trip my friends f800 used about 30% more fuel than I.
$3000.00 could buy all your accessories and a 2 week trip somewhere