I'm a very dedicated user of the subverter and I really like the bugger!
It fires only once and in strategic combat the AI would fire as soon as it gets within range, so the best defense is probably giving your ships as much defensive bonus as possible to make sure your opponent's first shot misses. Stealth armour + scattering armour + ECM III + legendary ship + legendary fleet can be quite devastating to a psychic player who relies too heavily on subverters. Repulser beams might help but max range strategy probably won't. The AI never runs hard enough unless you tell it to "don't get hurt".
I've tried to use both subverters and boarding parties in my fleets, but I never managed to get the boarding parties working properly in strategic combat. Perhaps that's why we haven't seen any AI or human players who use both.
[This message has been edited by CW (edited 19 September 2001).]