Depends on what you expect.
My Dak is great and is the reason I sold my 1150GS so quite the opposite to septic.
I do have an 1150RT for touring, but will be taking the Dak to the Alps this year as it handles better and will let me do a few off road excursions.
As for vibration with the 21" wheel, can't say I've noticed it.
Comfort is good (a 300 mile ride from Cornwall in -2 on new years eve was a reasonable test




).
Fuel is good, but the best is the all round ability of the Dak. I would hazzard that a few of the Derbyshire guys have been impressed with the Daks ability when I've been out with them (they know it's the bike and not that I'm a good rider



).
The bike is designed to do all jobs well enough. Obviously a tourer will tour better and a KTM EXE makes a better off road bike, but the Dak does both.
If you think it's heavy off road try laning on an 1150GS



Something I used to do and was impressed with it's capability until I got the Dak. It scratches down the b roads faster, off roads better and I don't get all the buffeting on the motorway. It's a ball ache of an engine to sit there at 80 all day as you need to turn your mechanical sympathy gene off, but it will do it and be reliable (unless you are Snoopy



).
Snoops bike had done 55,000 trouble free miles before it had anything go substantially wrong, can't knock that IMHO.
If I had to choose one bike between the RT and the Dak....it'd be the Dak. I asked the same question of the GS and it was sold.