What would you guys advise: one unit of 3, two units of 3, or one unit of 6? I'm playing a joint game with high elves vs chaos and vampire counts on thursday (2000 points per army, 4000 total). The plan is that he brings small units of elites (lots of special choices and a dragon), and I bring solid infantry to soak up the damage. So far I have temple guard, 2x20 saurus, salamanders, slann, scar-veteran and some camo skinks. Figure that the krox will bring some useful high str attacks (I'm thinking about knights here), and with a life slann should be able to soak up the wounds. Keep them on the flanks so they don't take things face on. Usually I bring krox in units of skinks though, so this'd be the first time I run them solo.
If your going against VC I'd suggest leaving the 6 unit behind as it'll attrack too much attention. However a unit of 3 is just as capable of handling combat and where one is good two is better. In short, 2 units of 3.