I've spoken to the guy who built it and he said that he always overlines this particular manufacturer's blank by 1 wt. Although I'm not a mechanical engineer, I would think that the action of the rod has some say on this as the stiffer "faster" actions will be slowed by the extra weight. Also, most rods that chuck larger streamers usually are faster action BECAUSE the larger, non-aerodynamic streamers slow it down...and for distance.
I really don't consider a rod like a 7wt to be used in anything less than 20 ft. I'm looking in the 40 -60 ft range. Not much more than that is my limit in my casting ability...until you put the 10wt in my hands, then I'm good to about 85-90ft. I really do need to practice more, though.
It's not the heat, it's the stupidity.
What manner of jackassery will I be subjected to today?