I have a late 2007 K1200GT. I had the software upgraded and the airbox replaced in separate operations, 2 1/2 months apart. Last February, the software was upgraded to version 10.0. Last week, the airbox was replaced, but the software version was left unchanged. (The service manager told me that software version 11.1 was available, but he had heard reports of problems with it, and did not install it on my K1200GT.)
Because the two operations were performed separately, I believe I understand how each one affected my bike in isolation. I would like to share my subjective experiences with the group.
Software Upgrade (15 February 2008):
This solved the twitchy throttle and overly strong engine braking problems.
Before the upgrade, the throttle was overly sensitive. The slightest movement would cause the bike to accelerate or decelerate way too much. Engine braking was much too strong, in my opinion. Riding over any bumps would cause the bike to lurch from the tiniest throttle movement, and the lurching would twitch the throttle more, making the bike hard to control. I worked hard for 8 months to learn better throttle management, under the assumption that this was a common feature of the new high-end sport touring bikes, but it was difficult, especially in the urban environment where I live. I have many years of riding experience, on many different bikes.
After the software upgrade, throttle control was easy. The bike no longer jumps at the slightest throttle movement. The throttle requires a little more rotation for hard acceleration, but it was so much better. It feels normal and natural. Furthermore, engine braking is reduced to a reasonable level. For me, it is perfect. If I want harder deceleration, that's what the brakes are for.
Airbox Replacement (29 April 2008)
This solved the BBS problem. It may have solved high idle problem, but it is too early to know.
I have only been riding a few days since the airbox replacement and only on relatively short commutes (mixed freeway and city riding).
I didn't realize how much BBS I had until after the airbox was replaced. The bike just wasn't smooth in normal operation. Since the airbox was replaced, the bike runs like creamy butter - as smooth as silk. The improvement was obvious and dramatic. This is how the bike should have operated from the very beginning.
Even after the airbox replacement, the K1200GT still "bucks" when I ride in first gear at really low RPMs (say, less than 2,000 RPM) in parking lots, but I didn't expect it to be different. I believe that this is normal. Feathering the clutch is appropriate in those situations.
There is still a hesitation when rolling the throttle hard around 3,000 RPM. It hasn't changed.
It is too soon to know if the high idle problem is also gone. It was very rare to begin with. I may never be certain. So far, so good.
The software upgrade and airbox replacement made a significant improvement to the rideability of my K1200GT. The K1200GT was a great bike and a major upgrade from my previous bikes when it was originally purchased, and I was very happy with it. After the software upgrade and airbox replacement, it reached an entirely new level in rideability. This is the way the bike should have been delivered in the first place, and it simply feels right.