ScottF,
I've tried several powders in K-Hornets, including my present one, a Brno ZKW, and 1680 was a distant also-ran to 300 MP in velocity. I may have a slow lot of 1680, but could not get enough into the case to come anywhere near 300 MP--and my 1680 produces velocities right around Hornady's results in the .17 Hornet.
Have a supply of CFE BLK just in, and while it looks to be a little slow for the standard Hornet, it may work very well in the K-Hornet, especially with 45-50 grain bullets--which may or may not be worth it.
