[Modernman]

What happens when Mr. Terrorist gets ahold of a smart helmet from a recently KIA soldier, and suddenly knows where every good guy is hiding?

I would imagine that it would be fairly easy to build safeguards in to such a system so that you use biometric information to ensure that only authorized users can access the information.

[LexBaird]

And I would imagine that any system can be hacked. If I were a battlefield commander, I would be highly concerned about having the position of every asset being broadcast to every other asset. It would give me great flexibility and situational awareness, but at the risk of being compromised every time a soldier, truck, or position was captured.

Countermeasures to smartsuit tech off the top of my head:

Spoof the enemy IFF transponders to disguise yourself as a friendly.
Flood the theater with false signals and jamming.
Counterfeit feeds going back to enemy HQ to give false data.
Tap into the enemy info feed and read their positions.
Blind them with an EMP to fry their smartsuit electronics.
Take out their comsats at a critical time.
Introduce a virus into their software.
Develop signal detectors that pinpoint where individual feedback signals are originating from.