I just returned from a 10 day trip on a rented 2009 BMW K1300 GT, and think this review might be interesting for some ST owners considering a jump to the far side.
Looking at the dimension specs, my ST1100 is very much like the GT. But, the similarity ends here. The bikes are totally different. My impressions of the GT follow. My ST does not have to fear the competition.
1. Comfort. For a sport TOURER one would think long distance comfort is a consideration. But, this is the most uncomfortable ride I've been on. I reviewed the bike before renting it, and came across one review that likened the seat to sitting on a split rail fence, with splinters. I learned to understand what that review meant. 1 hour in the saddle required a break. My hips felt like they were pried apart by the jaws of life.
2. Hardbags are BIG. This is obviously good....but not really, as getting on the bike invariably resulted skuffing the saddlebag. At 5'10" and 30 inch inseem, I found it impossible not to scuff the top of the bag most of the time. This must be a problem because the dealer glued a plastic foil to the top of it. These bags are heave when fill them. And, they don't balance to well off the bike and on the hotel room stand.
3. The brakes. Superb. Superb. So superb, you gotta watch your rear 'cause nothing following this bike will stop nearly as well.
4. Speedo/Rev gauges are not readable. The numbers are small, and what's up with the striations? One would expect large numerals from a German manufacturer, but not on this bike. The ST1100 has the gauges just right.
5. Tranny. Clunky. Not exactly top of the line.
6. The motor. Power galore in all ranges. I really liked the motor, but what's up with 4000rpms doing 80 with a six speed? This is supposed to be a tourer. The power and torque of the motor can easily match a Harley's 2800rpm at 80.
7. Wind protection. The windshield is electric. I never found a setting that is nearly as quiet as my ST1100's 22" shield.
8. This bike feels like a whale at slow speeds. It's the same weight as the ST1100, but feels 'fatter'.
9. Finally (?) BMW uses Japanese type turn signals. But wait!, why is there no quality feedback, feel, etc, for a 20+k bike? The turn signals are worse then the cheapest import I've ever ridden. And, no auto cancel? For a luxo tourer not good.
10. Ride. Great. But I didn't find a huge difference between the sport, komfort and normal settings. Cute, but not necessary.
11. Heated grips, seats and cruise control work superb. Best components on this bike.
After 10 days riding the autobahn 160+, country roads, alpine roads, parking lots, old towns with really small streets and tons of parked cars/traffic, I find it hard to cost justify a GT. And even if it cost 100$, I could not ride it longer then 1 hour, without major seat mods.