I don't remember what Lvl I was at, but the first time I attempted it (immidiatly after I got the choice to) I got my ass beat pretty quickly. I leveled up a BIT before attempting it again, but it was mainly my gambits that needed sorting out- Haste+Bravery on Vaan, Haste+Bravery+Berserk+Zodiak Spear on Basche, and Shell+Protect on Ashe at all times, plus the usual healings ect, and I was laughing. The Undying took a few tries, mind...

However, I think that SFB was the perfect length, considering the Paros was floor after floor after floor of the same basterd enemies with the same basterd texture on every basterd wall- it took me hours, and SFB was just 10- 20 of awesomeness. No tedium, just a few enemies, a few boss fights, and some of the best cutscenes in the game-what more can you ask for?