They do exist but they arrive late in the game and after the final dungeon... yeah you need them. The Dark Sorcerers are broken as all hell and don't deserve "fair play".

Zeromus wasn't exactly as challenging as he is in the Chronicles edition but just about everything else in that dungeon is... On the bright side, at least the true game breaker skill is only unlocked after you finish the game. I genuinely liked the Augment system since it allowed me to make Paladin Cecil much more useful cause god knows he really did need Counter as an ability. I don't feel the augments really break the game or take away from it cause very few are ever really overpowered and the few skills that can be considered are not easy to acquire with out a guide (Like Soul Eater, W-Cast, and Target All) so I see little harm. As for difficulty I guess that just depends on the player, I personally found a few boss battles to be much more difficult than I remember (Golbez anyone?) but others that other people have been having issues with I had no trouble at all (CPU unit and Zeromus). Its all in the eye of the beholder but personally I feel the game offers a pretty fun and new way to experience FFIV. Since it doesn't tamper with the story at all, I'm pretty lax about everything else and the game is still much more difficult than the GBA version.