I just went through my numbers for the season which I decided to go ahead and post after all. I had 35 attempts on 4th down. Of those, 34 of those were inside the 35 yard line -- so those are the ones that are relevent (the other was a late game situation where I was behind and it was 4th and 14 from my own 25).
If I had gone for the FG on each of those 34 4th down situations inside the 35 (51 yard FG) with a 90% success rate, that is an expected value of 91.8 points (2.7 * 34). That is 5.74 points per game.
Instead, by going for the first down those 34 times, here is what happened instead: 112 points or 7 points a game over the 16 games. That result is a 1.26PPG advantage over the EV over going for the FG.
While the +1.26PPG over the EV is nice, what is far bigger is that going for it on 4th down in those situations gave me the win in at least two games I would have otherwise lost.
BTW, my intention is in no way to encourage everyone to do this. This season was a rebuilding one for me and so I was free to be aggressive in experimenting. I posted this information to show a contrarian, "Moneyball" type approach -- not to say this is the one true path to GD success. It's a path that makes sense to me.