Not really balance, just weird ideas.
Cybran shields block other players' vision of shielded area unless other player has unit within shielded area.
UEF T3 "hypersonic" tac missile. 2x range, 2x speed, requires two hits from TMD to defeat.
Aeon ACU advanced sensor upgrade gives mini eye of Rhianne style quantum optics.
Seraphim sniper bots can target air units.