Personally I think pala > sage > heretic for an elf a/m/t. Pala has some very strong spells + -losses which makes him strong in defence(like the old elf) and plague immunity which is important because you are attacking. Sage sci bonus is very nice together with Amnesia. Heretic only provides bonus spell/op dmg and +1 mana(I'm not sure how good blizz is - when i was playing rogue I was ignoring it). I don't find that viable enough to be worth picking it over other options.