Hiya, the 1100/1150 is a modern classic, and production ended just as the GS hit the tipping point from cult oddity to mainstream popularity. Consequently they're in short supply now relative to the top-selling 1200.
My suggestion would be to get a piece of biking history while you can. You'll be able to take your pick of 12s anytime for the next decade at least.
The 12 does feel lighter, friskier and more modern than the 1100/1150, but they all have that confidence-inspiring GS pointy-squirty horizon-seeking feel to them.
This man talks sense

By the way, I've had an R80, R100GS, R1100GS, and my current 1150GSA over the years. First time I rode the 1100 after the R100, it was a revelation, a massive leap forward in my book. Did 80,000 miles on the 1100, then sold it 7 years ago and bought the 1150GSA, which was my dream bike at the time. It's served me well over the last 120,000kms, but I'm going for a test ride on a 1200GSA this Saturday...



Sunday wisdom from Den