I think if a bullet whizzes past you, you should instinctively look in the direction of the bullet, while also making some reflexive motions for cover. This would A) make suppresive fire more powerful, and B) make it easier to find out where people are shooting you from if you look in the direction of a noise.
I know thats controversial, but I 'm on a 12 inch laptop monitor with small little speakers in the front (so from one direction), this seriosily handicaps me in both the visual and sound department. Visually, alright, but if the game instantly recognized where sound was coming from (something people are pretty good at in real life, but game sound is very hard to find the direction from) it would help some. I think it would also add to the immersion, etc.
Mostly, though, suppresive fire needs to be devastatingly suppresive, while still often not deadly.