4/6/31 is our highest burst and sustained DPS spec. I've played it and the damage output is superb.
That being said, it has several downsides:
- it lacks a charge or in-combat sprint
- it's squishy
- the spec has no synergy with Guard
- the CC capability relative to other specs is limited
4/6/31 basically is "a good defense is a good offense".
Iron Fist offers much more utility and survivability. The difference when taking focus fire is night-and-day.
So it really depends on whether you want to be an all-out DPS or an offensive tank. The latter is more what I'm looking for, and the reason I rolled a can-tank AC in the first place.