If your local players are taking something like that against you, there are ways to counter without being completely broken. For one thing, Archaon and a huge unit of Chaos Knights like that are over half the points allowance at 3k. Even with Magic Resistance 2, just casting away with Lore of Metal, combined with baiting and redirecting can keep this from being an issue. I'm not sure about Kurt Helborg and Karl Franz, as no-one here plays Empire, but I'm sure that there are similar counters to that unit. If it becomes that much of a problem, simply run counter-lists to them. A games no fun if you get wiped off a table, and, depending on the person, even the winning side feels the pain.
Which is actually a lie. There are plenty of ways to counter units, especially those as lopsided and gimped as the ones you've described.
Lets use the Chaos Knights as an example, that large a unit is easily redirected by bait-and-flee tactics, and is quite vulnerable to the right shooting and spells. Cannons and bolt throwers will eat through that unit like nothing, and the Lore of Metal could easily kill 6-7 of those with a single spell. Seeing as how they'd have the numbers you posted, the warriors would have practically nothing else other than that unit, and you could redirect everything that is not geared to kill them against other stuff.
