This is the two tanks in a nutshell, though I can't speak on Warrior's feel other than absolutely crushing whatever it is that was stupid enough to fight you.
Dark Knight is very busy and is actually a little multitask-y, which is why I like it. Flitting around aspects of the fight managing this or that ability on this or that mob, and when it comes time to single-target dumping everything in the proper order consistently. Busy, but engaging. Warrior just lets you feel badass for far more straightforward practice than the oGCD micromanagement of Dark Knight.
Warriors will always have raid slots available, though, unless encounter design philosophy changes drastically come 3.1. Dark Knights... from the sounds of the next Savage tier being mostly Physical, it's sounding like DRK and PLD are going to start playing a long game of Irrelevance Leapfrog in the bleeding-edge meta that everyone forgets is bleeding-edge and not standardized.
