I'm all for critical hits for naval, air and tactical space combat, because at least for the first two genres critical hits seem to play an important part in reality. I'm not so sold on the idea for operational games, but I guess if your main units are naval, there might be a case to answer. I think the mechanics of the critical hit are more important to the tactical level, whereas number crunching is perhaps more relevant at the operational level... the tank is dead... does it matter whether the fuel supply blew up, or the ammo...?