Thats pretty poor fuel economy. I doubt you will get much better after break in. Well the Honda 300 was less than half the engine displacement, so I would expect better mileage. Now, for your type of riding, do you need the extra power of the BF 750? If not, I would consider trading down in size some. If your riding is generally short distance stuff then it may not be as big an issue either.
It's not the Kawasaki that is drinking the gas, it is the engine size. If Honda made a 750, it would likely drink the fuel too. Maybe something in the 450 to 500 cc range would be better..