Cloaking in NS should be approached like walking around wearing a cardboard box in Metal Gear: You move (walk) when the rines are looking away, then stand still when they turn around. Remember, the closer you are, the bigger you appear on their screen, and the easier it is to spot you if you're not completely invisible. When standing still, you are completely invisible if I'm not mistaken. If you're still far away, it may be safe to move even if in full sight of the enemy, but don't come crying to me if it gets you killed.
Basically, what gets a cloaker killed is growing overconfident. If you are not 100% cloaked, you CAN be seen. At 5% it's hard, but far from impossible, much further than you'd like. It's almost as if fate has a sense of irony: If you believe you cannot be seen, you WILL be seen.
Cloaking is a mighty upgrade if used right, but it's NOT flawless or almighty. Not overestimating its usefulness will allow you to utilise it to its best.