Keep what you read in perspective. The fact of the matter is that the vast majority of GT owners are very happy with their bikes.
I just purchased my '10 GT and had some of the same concerns as you after searching the forums. However, the 13GT has benefited from many improvements, and I feel very comfortable taking the bike anywhere.
As for the C14, I also considered it. Honestly, it's hard to compare the C14 to the '10 13GT. The K13GT has nicer ergos, better wind protection, longer range, more power, nicer handling, and all the amenities you could ask for.
It's your choice, but if you can swing a GT, I don't think you'd regret it.