Originally posted by der schwarze RitterIt has been played before, it occurs twice on my database and the position after 5. f3 occurs by transposition a further 6 times. The only game where ratings are quoted was between a 2244 player and 2285, so they aren't pushovers. Having said all that your intuition is probably right as white lost in all but 2 of the 8 games, the 2 games that white won continued 5. ... dxe4 as in the game here.
"f3" looks suspect. You had better study the French some more.