Not sure I won't regret this, and I've avoided getting involved with any of these threads on the forum because of the likelihood of getting flamed
Seems like telling anyone that there may be a "better" bike than the one they currently own is like (or maybe worse than) calling their girlfriend ugly
I have an 07 GS (not GSA) which I have covered about 16K miles on - mainly "progressive" road work, both on my own for Sunday blasts and with my wife and luggage around Europe on holiday.
It has been extensively modified, all with the aim of turning it into the best possible fast road mile muncher, and fun steed for hooning on the twisties.
http://www.ukgser.com/forums/showthread.php?p=1681164#post1681164
I think it is a brilliant bike for the road, and I have never really had any desire to take it off road (hence the road tyres, stiffer suspension, etc).
Whenever anyone asked me about it I would say "Don't think a GS is slow and boring - it is a very capable bike, and can show a poorly ridden sports bike a clean pair of heels on anything other than a race track."
If pushed, I would admit that "the things that would improve it for me (making a good bike a great bike) is a bit more power, a bit less weight, improved handling, and a more "exciting" engine character."
Hence the reason I tried a Multistrada - because it had all of the things I like about my GS (comfortable, practical, commanding riding position) PLUS it seemed to address all of the things that I thought could be better.
On the test ride, I loved it, and truly felt it to be the best bike I'd ever ridden in over 25 years and countless bikes, BUT the fueling was shockingly bad, and I said I'd never buy one unless Ducati sorted it out.
I'm happy to say that this has been done, and the fueling is now pretty much perfect (better than my GS was pre power commander).
So, as a fast road bike, capable of covering serious distances in complete comfort, then having a great laugh in the mountains or whatever when you get there, the MTS beats the GS hands down IMHO.
The Ducati is significantly faster, quite a bit lighter, has much sharper handling (even compared to my Wilbers equipped bike) and, for me anyway, it is more comfortable over long distances.
As a full on adventure bike for crossing continents on unmade roads, then I don't believe the MTS is the right answer and you would be better to stick with a GS(A), or maybe even a more dedicated off road machine.
Having said all of this, I have not sold my GS (yet) because my wife loves it so much we've decided to hold on until she's had a chance to try the MTS pillion over longer distances.
Mind you, she loves the GS because it is mega comfortable on the back and the power delivery is so unintimidating that she can sleep on the back even when I'm riding "progressively" - so her criteria for a good bike may not necessarily match mine
I've tried to make my feedback here as balanced as possible, and I'm not trying to start a "My bike's better than yours" debate. But the question was asked and, in my opinion, the MTS is a significantly better ROAD bike than the GS in pretty much every respect.
I genuinely hope that BMW will respond to the MTS and put some serious effort into a new GS that returns it to world beater status. The S1000RR has shown us what they can do when they want to, but the recent revisions to the GS have (IMHO) been a bit lazy - doing just enough to retain the current customer base without trying to move the bike along. If Ducati have given them a kick up the arse which results in a big step to the next model revision, they will have done us all a favour