I generally don't run to completely E either, some people believe it's hard on the fuel pumps as the motor is no longer submerged in fuel acting as coolant for it. I don't concern myself with that, I just know where gas is cheaper and watch my range so I can make it back there.
Ethanol content can affect your MPG some, E10 has about 4% less BTU's per gallon, some cars follow the energy to mpg curve and will lose 4%. Others don't.
http://www.speedperf6rmanc3.com/cont...evel_Study.pdf
In that study one of the cars they used a 07 Camry 2.4 and ran different ethanol blends and recorded MPG and more. It actually got the best fuel economy running E30.