I just sold my LT. And know for a fact that before to long my 05 KS will be traded into either a GT or RT.
I think that as far as riding position, ESA, options (Cruise, H grips and H seats and saddle bags) the bikes are nearly identical. If you think about it even price they are pretty close, by the time you put all the nice options on an RT including the top trunk you are boderlining 20K, so. But off course there is also were it DEAD stops.
GT more power, water cooled engine..... And those two things might be the deciding factor for me.
I used to own a 04 R1150RT, and could never get used to the vibrations (which I hear are better now with counterbalancers), the dang oil comsuption (which is also supposed to be better) and the plain and simple fact that IT IS an aircooled bike and if AIR is either NOT blowing right thru it (bumper to bumper traffic) or the air is HOT as hell as it is here in GA right now the bike will run hot. And again the fairing design is new but on the 04 RT's they GOT HOT to the point where paint right over the cylinder head would look like it was "melting".
So I might end up with a GT, would love to see BMW make a red one, Titan Silver and Black on the GT.