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Krootox... I'm not terribly certain why GW did these things like they did.
If they'd made the single change of being able to attach them to a Kroot squad just like every other support weapon for every other army in the game, then they would be an awesome unit.
However, soaking up a Heavy Support slot like they do kills whatever usefulness they may have had. That's a ForceOrg slot better spent on another Hammerhead.
Now, Kroot hounds, however... these guys are just awesome, and since I never use Kor'vesa or pathfinders, burning up my Fast Attack slots with them is no problem.
i agree with nightwalker. krootox are wastful, you can buy a nice hammerhead for the cost of 3 krootox and the hammerhead is much more efficient.