Yet another idea, and I've discussed this a bit with Zay, is to have some sort of AI reaction to suppressive fire beyond the standard "go prone, turn to face threat, shoot threat's head off" routine when you fire at an AI. This is something of a continuation of your variable idea, Chris.
Maybe have a global variable for each soldier (that you'd like) that represents his anxiousness/efficiency rate. This could even bounce off of the skill setting used in the mission editor, so that the more experienced soldiers don't react to suppressive fire as bad as the rooks.
Here's an example scenario. A light US patrol is walking along the treeline of an Everonian forest. It's mostly a novice patrol, the highest ranking officer of the bunch only being in-country for 2 weeks. The rest are fresh replacements. Out of nowhere, RPK fire lunges out at them from the belly of the forest. The gunner is an elite Red Army regular, a veteran of the Afghanistan War of the 70's. He is attached to a squad of long-time comrades, on a recon mission. They've found the light patrol, and decided to seize the opportunity. 3 of the US soldiers are killed instantly. The rest jump for any cover they can find. The relatively low skill level of the soldiers and the fact that half of their patrol was just waxed makes them all nervous, scared, and panicked. The fact that they were surprised brings their morale down even lower. They freeze under the suppressive RPK fire, the fledgling CO without a clue as to what to do. Out of options, the young CO fires a wild spray of bullets in the direction of the machine gunner. The rounds land mere inches from the RPK operator's body, but he is unfazed, only momentarily ceasing his barrage of bullets. The Americans realize all too late that half of the enemy squad had flanked them. Their deaths were quick.
Imagine if that scenario could be played out with the use of scripts. I think it's possible. Every soldier would have a "anxiety level" or "morale" that would be influenced by both skill setting as well as circumstance (whether the enemy surprised them or not, casualties they've suffered).
A good example of something to borrow from is the freeware game America's Army. In the latest build, they include a "Combat Efficiency Meter." It represents your accuracy at the current time. As is typical, stance, speed, etc. affect it, but so do circumstancial factors. If someone is shooting at you, it plummets dramatically. If an explosion goes off next to you, it decreases even further. If you're wounded, it also decreases. You get a small bonus the closer you are to your squad leader (simulating the CO encouraging his troops to fight on).
These and other factors could and should be implemented into OFP. Who's with me? ;D