I'm not overly knowledgeable on the historic performance of the Brewster, but looking at it, I think the one we have in game is a tad overmodelled. Oh I love to fly it in base defense, but it manages to attain 300mph in a dive and then just doesn't seem to want to lose that E.
Compared to it, the F4F or even the FM2 (which in my opinion shouldn't be too far away gauging from the ironing board and barrel design) feels like a brick.