I tried that as well Bustr, same result in every plane with the 4 post lighting on or off. Shadows off I find has a huge effect on the general brightness of the game, example go into the hangar and look at the ground with them on/off, but that doesn't really affect tracers for me either.
I really think that the reason people are seeing the smaller tracers is due to their not being smoke behind them as before or the same as AH2 has been - so far as the sprites, yes, they're smaller, and it's debatable if it's more/less realistic, and it will affect gunnery, but IMO, it's HTC's decision so far, and I'm not too fussed about them. Again, IMO it rewards more accurate shooters, and makes gunnery harder. The argument is there that in AH2 gunnery was very easy, maybe too easy, who knows. Sakai said getting hits in the air is akin to shooting a butterfly with a rifle, so who knows, maybe if it's made harder through more difficult trader/hit/damage eye tracking, it'll make the gameplay different, and perhaps more interesting.
HT did say he's adjusting the smoke/tracer trail in the next patch, so I think waiting until after that before getting worked up is probably best.