The problem with Early Warning Override on Crisis Suits is that for it to work, the suits must be on the table. Crisis suits are MUCH more valuable when held in deep strike reserve themselves ("Manta Strike") then bombed in (Homing Beacons FTW). I've tinkered with Shield Generators on my suits, but typically the Crisis team is inside rapid fire range and gets wasted by failing 3+ saves rather than by special weapons. In either case, the third weapons would pay dividends.
Advanced Targeting System (-1 AP to all weapons) seems tasty, but Tau shooing isn't very good so I think an extra chance to hit >> better wounding. The first step of Marker Lights is re-roll 1's, so you'd have to be crazy to sacrifice more shots for the Multi-tracker (re-roll 1's).
Guess that answers the question, eh? MOAR GUNS.