Okay, so if the L & J fly the same other than the L having a better roll rate then why choose the J, other than cosmetics or perk farming because I dont care about either. In short IS the L a better choice for dog fighting in?
Head to the DA. Alternate between the J and the L so you see for yourself. You will be up against spit 16, f4u4 and the like but it is really good practice. Use the ammo load-out that suits you and no less than 50% fuel so it compares with the MA use.
BTW, Bustr has a really good historic gun sight for the L that has a rocket ladder