OK, that was just awesome.
I'm glad to see Elend has stayed true to his core; chapter one had me wondering. His actions with the townspeople probably saved as many of them as possible in the circumstances. Without his leadership and Allomancy, they would have all died. He was trying to take control of the Koloss, but because an inquisitor was controlling them, it took special circumstances to take control, and having the townpeople fight was crucial to getting the upper hand.
His actions seemed rash, but now that we get a feel for the kind of enemy that they are fighting, it was clearly the best he could do in difficult circumstances.
I agree that Elend has stronger Allomancy, but Vin has better training and control. At the moment that means they complement each other, because as Kelsier said, Allomancy is nothing but tricks. Timing is still critically important and Vin's fighting has an elegance that Elend still lacks.
Incidentally, I think it is safe to say that Ruin is controlling the Koloss, but it is doing it via the Inquisitors. When the Inquisitor died, Elend was able to take over. But man was that close. And yeah, it seriously looked like the Inquisitor was using Feruchemy. Man, but that is a scary thought.