It's a lot harder because of the scary skills the enemy units have in the 4th and 5th, ie: The Snipers have Counter + a skill that makes the damage from Counter doubled, the Beserkers who have 99 HP with Luna + and Counter, and of course there's Anna with Vantage +, Counter, and Aether...
But it's still managable as long as you have a lot of Galeforce units, good Rally bots, a few Rescue staffs, and Olivia as a Dancer couldn't hurt.
Mmm, do you wanna see my units who beat the secret path? o: Could give you some ideas!