Sentinels/Marauders, the new 4x DK?

[Apatheist]

I'm thinking 90% of the time my points will be used on Zen rather than the run speed buff. With Watchman spec you already get a static 30% snare and 11 second charge. I can't imagine I'll have trouble staying on top of people, provided the lack of IWT isn't an issue. Being able to AoE heal 18% health every ~15 seconds plus the 2% on every DoT crit is pretty boss.

The only issue I have with the group is Sentinels can't tank. I wonder how much of a damage loss it would be swapping one Sentinel for a Guardian.