When he's also a high level Duelist.
Otherwise, he'll never measure up.
He'll have advantages in terms of mobility and certain skills, but he'll be matched in terms of AC and outclassed in terms of damage. Weapon Finesee is nice, but it basically restricts you to weapons that do 1d6 damage, and without a good strength bonus, that's a real problem.
Also, Spring Attack and Expertise games are fun to play, but you have to remember that the only time you get to play them (assuming the rest of the party isn't willing to put up with watching your "Flit like a butterfly..." BS and taking all the melee damage while you hide behind the cleric) is if there's a more traditional tank in the group to take up the slack in terms of front line fighting and damage-dealing.