That's why I said faery is more resource controller: with fb/lighting strike/tornadoes you do more dmg I agree but you dont need mystic perso for them. The best about faeries is they have also tog. While elves should do pf/ms/chastity which consumes a lot mana/runes, faeries can do everything else better or they can feed dragon fast if needed. Should you spend a whole perso just for +1 mana... I dont think so :). Now this will be my last post about that because its off topic...
About the topic: generally if u are going to use your thieves for something more than intel you will need atleast 10% TDs. Are you going to have the room for them is another question. Also when war starts you will lose/gain land and your tpa/TDs will drop so it will be harder to do other ops than intel and to be honest: i really hate when someone of the attackers in KD spent his stealth for something else than intel.