How well do Great Hunger hold up in a campaign?

I'm considering playing The Great Hunger in a campaign, but they seem problematic from my novice perspective and I'd appreciate advice.

The way the faciton works in my eyes is that it has little by way of ranged attacks, equipment (e.g. no thrall grenades), and armor-piercing, but in exchange gets speed and durability (except against fire and explosives).

In a one off small game, this can make The Great Hunger very powerful.

But later on, I'm worried that the faction's strengths will not scale in line with opponents' abilities to take advantage of weaknesses. The hag's powers and the units don't become vastly more powerful, but the opposing forces will increasingly acquire fire weapons, explosives and armor that work as hard counters.

I can imagine, in a match with slightly less terrain, marching the horde towards enemies with a decent firing corridor with some grenades and a couple flame weapons and half my force just getting melted away.

What have been your experiences? Do The Great Hunger still stay competitive in a campaign? What strategies have you seen to keep them competitive?