If (or should I say, "when") I snap off my wing in a race, I notice it on my buggy. On the truggy; no so much. It seems that the gyro effect of the big spinning tires compensates for any loss in stability due to a missing wing. Plus, the wing on my Losi sat so close to the body, there was very little clean air going over the wing anyway.
Now, with the cab-forward truggy bodies, this may be a different story since the wing is more exposed, but again, you've got the big gyros at all four corners. On high speed straights, maybe that nose does help. But the cynic in me says that any benefit is bogus marketing hype; at least with a buggy. There's a shock tower out front, so there's no clean air passig over the body.
Long story longer, for me, the body is never a consideration when doing any sort of set-up for a track.