Actually guys, out of 6 players, we have 5 playing Striker roles, and only 1 Controller, and there are no Defenders or Leaders at all. As the party stands, combats will probably be lethal to a player or two per encounter, since there are no healing or protective roles, and the party will thus be limited to using guerrilla tactics and hit-and-runs. It could work, but I still don't see you guys being able to hold your own in melee very well, and save for the Dwarven Infernal Warlock Twins (I love how you both picked the exact same character type
) you wont have much of a way to avoid enemy melee, lacking in ranged damage and Defenders to hold the front line.
I'm willing to run it this way, but it will take careful tactical decisions and teamwork. Still, to avoid frustrating you all in combat scenarios, if a few players would be willing to branch out into Defender or Leader roles, it'd help round out the party. Also, there are a wide variety of Races to choose from, some more uncommon than you'll generally find in 4e campaigns, so feel free to try one out. If you end up not liking your character, we can always make you a new one.
Since I tend to do a lot of non-combat challenges as well, the party may want to consider investing in some varied skills (acrobats, trackers, healers, scholars, diplomats, etc.
On that note, Yanlin, maybe you'd consider playing a Swordmage? You'd have the martial capabilities and armor of a fighter, plus the elemental damage and utility of a Wizard, and it's not a watered down cross-class as in earlier editions.