I will share the opposite experience.I have a slightly better win rate in my La9 compared to my I-250. Its only a few percentage spread though. Like Dave said, check the survival ratio on each plane. when you compare more points it will give you a better picture. You might also be going in heavy on the furball, but not surviving the battle. Once you die and you are the only human in the battle, its a good chance that you will lose. Especially if the enemy team's human(s) are alive.
Just a heads up, the La160 will be different than the other planes in this line. Luckily they did make it better with one of the patches, Grinding it was painful. Last few times I played it, they made it better. Try to free xp past the 37mm cannon, that thing sucks(or at least it used to). The 30mm cannons used to shoot like the TA 152 30mm cannons, but they are better now(they shoot faster).