In my first game as DAK (maybe my 10th game overall), I was hit with a player literally spamming them. 4-5 of these Sappers, all with flamers, and then Indian arty (heavy mortar and arty emplacement). That was very very effective...
Upgraded 250 hardcounters it completely.
And since you're going to be calling in AT squad, you're going to have 250 if you didn't identified what opponent does and built one earlier already.
BOYS AT spam is much more scary.