True, but then I'd probably look to implement it like this:
Say you're character "A" has a 50% hit rate. He manages to hit an alien, so his next shot he gets something like a +10% accuracy, which means he now has 60% chance on his next shot. If he misses, he only drops back down to 50%, so you're at no loss, it's just an extra when consistantly hitting. It'll only remain during the mission too. I'm assuming the accuracy still increases over time of hitting in the new game, like the old? So naturally, he should build up his accuracy better, to the point where you could maybe exclude them from the "streak bonus"
I wish there were some better details on the abilities you could give you units too. I give my sniper the ability to take shots for free (can't remember what it's called off-hand), but sometimes it does, sometimes it doesn't. I'm assuming there's a rule to it, but it's not very clear IMO