Are you referring to the engine coolant temp or the heat felt by the rider?
If it is the "felt heat" the rider has to put up with, I can partially answer that.
I have an '04 ST1300 and my Dad rides an '07 FJR (Gen2). I have never ridden the C14. First thing is that not everyone agrees on how much heat the ST1300 produces. I don't much notice it, it has never been an issue. The Gen 1 FJR ('03-'05) was pretty bad about rider heat. The Gen 2 FJR ('06-'12) is about the same as the ST1300. I honestly cannot tell the difference temp wise between the two bikes and I have ridden them both in the heat of the summer. The Gen 3 FJR (2013) is supposed to have improved the heat situation even more. I have not ridden one.
What part of Swampy Flatlandistan are you in? I am not far outside Baton Rouge, if you need a closer look at the ST, let me know.