I have ran my pickup (7.3) without a fan for over 2 years with zero issues, DD, towing, whatever. I recently added it back because my block is filled and needed a little extra insurance that things wont get too hot. I did not notice any difference in fuel economy, but it felt like it had a little more ummmph without it. It is also nice because it quiets the engine noise down too.
As for the electric fan....................not a big fan.
I went through about 3 different fans on my OBS (5.0) and they each left me sitting at home because I could not run without them (living in Phoenix at the time). This left me with a sour taste, as the reliability was NOT there. I am still using electric fans on that truck without any issues but I had to pay a pretty penny for them.