I suppose it's superfluous to point out how useful such a "real-time moving map showing where all your men are" would be for an enemy too, so a remote kill-switch would be pretty essential, I imagine.

Only I can see trouble walking round with soldiers head down while unequipped opponents (keeping their heads up) just wait for some one to come within range.

And as Lionel Baden pointed out battery failure on *your* unit will be *very* unfortunate for your team membership.

And I think we all know what even someone as follicly challenged as Bruce Willis could do with access to his opponents radio.