The ability to hold a button or toggle a function to change the player's movement speed to walking or sprinting, the current speed being the middle, I think would greatly increase the game play and add a level of skill. Walking should only be available in Haven, but the addition of sprinting would allow players to catch up to other players and run away or toward enemies, for instance with sprinting you could run out of the reach of the big wolver's attacks. There would have to be a time limit to how long you could sprint, like in Lockdown. You could also get trinkets that would increase your sprint time, and if you are wearing heavy armor you'd lose the ability to sprint altogether, or lose a large amount of sprint time.
There is already a thread for sprinting of sorts but it is more like charging than sprinting. http://forums.spiralknights.com/en/node/17258
yes, but not as long or fast as lock down