My issue with a single zoan though is the loss of an elite slot. This slot is been fought (mainly) between Hive guard, Zoans and venomthropes. This edition might also see an increase in Lictor use and perhaps even the Haruspex (though really still not sure what to make of it).
So personally feel you are wasting a slot on just a single zoan who isn't really going to see much action. But again my views.
And I've not played with nids for a long while, but I vaguely remember that they can't take fortifications. or have I got this wrong?
“Insane? You dare to claim that we are insane? I find this very amusing. You see, there is no such thing as sanity. Why? Because the nature of sanity depends on the context the term is used. A man living in squalor may call the rich man insane for wasting food, while the rich man in return may call the poor insane for living off his waste. You slaughter thousands and squander the resources of planets on foolish incursions to please a corpse and his corrupted followers. And you have the nerve to call me insane? Oh poor misguided individual, pray to whatever deity you serve and hope he is merciful, for those who find themselves trapped in the spiders web have little else they can do”
Lord Nerthro of the ‘Heralds of Absurdity’ to what remained of an Imperial scouting party