Definitely on the high end of sweat loss...

Finally went through the trouble of doing the necessary steps to determine my rate during my two hour run tonight. Weighed myself and my full water bottle pre-workout and myself and empty water bottle post workout. No other water loss along the way. Total weight loss: 7.6 pounds. Sweat loss rate: 1.74 liters per hour.

I always figured it was above average just comparing the way I sweat to people around me, but that's pretty high for a guy 5'8" and 163 pounds.