Black Hawks are amazing with flares now as it allows you to fly slower and lower to the ground. This lets your gunners have a better chance of killing. Then once you get tracered drop the flares and start flying erratically at full speed while the flares are on cooldown.
I like flares, but I like pilots who fly slow and low even more.
When I'm playing Engineer, there's nothing easier than RPG'ing a low and slow blackhawk. No need for a tracer dart. When I'm playing any other class, it's very easy to shoot the chopper pilot through his windshield when he's flying slow and low.
I have no problem destroying helis as a tank gunner, you're target is gigantic and relatively slow, you have a weak gun that can swivel faster than he can turn, has a high rof and is very easy to lead with even at long ranges. It also helps that many pilots become very overconfident with a few heli kills that they hover more and strafe less but even independent of that behavior, it is still very practical to consistently destroy attack helicopters with tanks, mounted MG and AA guns. What is so unrealistic about that?