That would lol.
SAO vets: The. Fuck.
ALO players: Who's this due?
Lvl 75 Clearing survivors: Shit just got real.
That said it's been noted that ever since Aincrad was ported to ALO, boss fights and normal monsters are a lot more dangerous... Probably because not all of the SAO sword skills were ported, perhaps.
On the other hand, Asuna practically soloed the level 21 boss, so...
Her POV 3rd person narration claims she forgot about healing and was consumed by a desire for combat and securing her little house in the woods and charged right through Klein to kill the boss.