Oh, the Pyro-GX I can handle. Lemme do it, Lazlo.
And can someone tell me WHAT this G-Diffuser is? I haven't played Starfox 64
Now then.....
I think the Arwing is purposefully kept to be kind of tippy, so as to do much more effective barrel rolls. Look at a more balanced ship, like the Pyro-GX. That thing has pidly barrel rolls.
The Arwing, however, can use violent barrel rolls to avoid many laser and other attacks, and can use the tippy wait to make more sudden moves to the side when tipped over. [like when you hold down L, you can turn to the left better, right?]
As for the lack of lift, I think with space ships it can hardly matter, since I'm sure they can move at suck speeds that the slightest orifice would provide massive quantities of lift.
But maybe the Arwing is a Lifting Body design, where the whole fuseloge is in a certain design to provide the lift it needs, so as to minimize the wing size.
Any other theories? [yes, I am pretty experienced with aeronautics.]