I bought a new 2010 BMW GS Adventure after much deliberation. $24K OTD as equipped with almost all of the Goodies. I really liked the way the RT rode but it was Not Price Competitive with ST1300, 2007, left over, In The Crate, for 12.7K OTD. I have a Honda Dealer and a BMW Dealer within 7 Miles of my house. The Honda Dealer will let you test Ride a Goldwing after Your Check Clears the Bank and DMV Registration is Done. BMW Welcomes Test Rides. Honda Dealer lets you know after you let your ride leave that they were wrong and your bike is not ready, In Fact They Haven't Even Started to work on it YET. BMW will call you if there's a problem and will give you a loaner Bike. Honda will let you use the Shop Phone to call yourself a Cab. I do all of my own work, Tires and Balance included. I don't care what the Services Cost.
ST1300 is a great Bike and a Fantastic Value. Honda Dealers, Not So Much.
R1200GS Adventure is a Niche Bike. It's a Very Fast Mountain Goat with a Lot Of Cargo Capacity!
Both Bikes a terrific. It just depends on where you are going and what you are doing.
Well, I suppose there is only one logical choice then: get BOTH!!!