Fine, if that's what the data tells you. But I'll go back to my earlier point...if you're going to follow the data, you must do it ALL THE TIME for the law of averages dictated by the stats to do their work. That's clearly not the case in an occasional attempt to go for it, and invoking the stats in support of the occasional attempt is a falacy.
In further support of my earlier comment, the Cornell study found this regarding the outcome of 1st. and 10 from your own 20 (very similar to the Packer situation):
"The team with the ball is slightly more likely to score the next points in the game (1628 times the next score was a touchdown by team A, and 1413 times the next score was a touchdown by the other team)." In other words, the value of the first down in that situation is not persuasive, as I noted earlier.
I view the the 4th. and 1-or-less data with some skepticism. You'd have to think those instances in the data set are weighted toward trailing teams later in games. And a certain number are teams trailing by a wide margin at any point in the game. In these instances, the defense is not likely to sell out for the run, are playing prevent, or would gladly trade a first down for 40 seconds burned off the clock or a burned time out.
I'd be a lot more agreeable to the call if it's on the opponent's 35 yard line on a cold or windy day. The FG is a dicey proposition under those condition; the punt could go touchback or short out of bounds causing you to lose the field position advantage, which is what punting is all about.
Unless and until somebody does it ALL THE TIME, and leverages the 4 down run/pass series (which could possibly be a powerful strategy) by imbedding it in their offensive play call strategy (and even their personnel selection process), I fail to be persuaded. With the kickoff rules as they stand now, ditching the punt entirely relieves you of the need to keep quite as many guys who are coverage specialists. Maybe Denver should try it? The Jets?