Lack of guardians shouldn't be that big deal (except when you want to goldmine only with guardians) but lack of phalanx would show very fast and i doubt, given the power of imperials archers, heavy spearmen could be solution even in horde.
Imagine solution. 1 million phalanx, 400k elite archers, 500k guardians and 500k paladins goes against nomad (in my old era that army is very possible)
What a hell you can put against that. Cavalry?
? Elite archers
I did a battlefield calculator with the army I would create for nomad and I win. I estimated all researchs 20,20,20. I had nomad in defense on neutral ground as I am playing nomad at the moment. I looked at the imperian army cost and with that cash I managed to make:
200,000 javalin men
1000000 heavy spear
1000000 heavy sword
400000 elite archerer
700000 paladins
200000 cataphract archers
and I win. 2.4 million man army vs. 3.5 million.
the costs of the army are Imperian 1,501,400,000 wood and 483,000,000 iron upkeep 1,920,000
and nomad 1,016,400,000 wodd and 429,800,000 iron upkeep 1,777,000
The only thing I dont know is if the nomads can make enough humans to fill a 3.5 million man army! But if they have a 200,000 pop cap, then I guess its possible. It was alot of numbers...i hope my math is dead on!!!