this is my army list: http://www.lustria-online.com/viewtopic.php?f=8&t=9460 so the 4 krox or something else?
Hey, I've been contemplating a similar thing with the kroxigor. The only real weakness is that you have to protect them from missile fire. I would do this by screening with one of the skirmisher units (gives- I believe- hard cover). I'm starting to think I prefer running a 4 man krox unit instead of skrox because they're more manoeuvrable and don't give easy CR. Anyway, I'm still thinking about it so someone else may have a stronger opinion
I like the 4 and 6 man unit of KROX; run them 2x2 or 3x2. They are quick on the flanks, hard hitting and people seem to get nervous when they see them and often make moves to adjust for them; which opens up other opportunities for you. Just remember with no banner in the unit, if KROX unit gets charged they are 90% of the time already fighting from a deficit of -2.
As much as I like Krox I have to say go with the Ancient Steg. 7th edition Krox were great! 3krox getting a flank charge into almost any unit would be 4-5 dead. But with Initiative vs. GW for striking order Krox just arn't hard enough anymore (unless you are flanking Scaven slaves/clanrats/spears). Ancients has those drawbacks as well but it has: higher Toughness, 2+AS, imact hits, great blowguns, and terror. All that on a 50mm frontage. Don't get me wrong, I still have 4 Krox in my list. They just have some ablative armor(ie, 48 Skinks) to soak up some hits.