I'm sorry but whilst Sorc may have extremely huge burst. It's all luck based.
They freeze someone, JT is parried, Spear misses, now what are they going to do? When I play Sorc in colo I get a kill, and then get killed myself because I get knocked down by some Sin or CC chained by some Warrior. Deluge, LoR? They do nothing without Earth Seal. It also doesn't stop people trying to kill to just kill you anyway.
The truly imbalanced class in Colo is Priest. Unless you get that 200% Attack to tear them apart, trying to 1v1 them is a waste of time. They heal themselves to full one time, and people stop focusing them instantly. "The guy just used his 5 minute cooldown to save his ass, why be stupid and stop focusing him...". They just DoT everything INSTANTLY, they run around with their Ray of Genesis casting (why the hell does a Ranged class get to move during casting? Rogue gets locked in Duration for their Moonlight Dance). With VIP they have 11k+ HP, Movement Speed buff, 40% Damage Reduction. Heals over time,
Also why is VIP enabled in Colo, gives such blatant benefits with the HP buff and Movement speed. It's a joke when squishy ranged classes run as fast as an Assassin (guess I need VIP for more movement speed on my Assassin..).