Over in a thread discussing Jackal armour, StellarRat said:-
that got me thinking, what were the most challenging missions for everyone else.
For me there was a big jump in alien numbers from 7-8 to 21 in my first Alien Base defence in 19/4. Not just the numbers but the alien rank increased by a couple of steps as well. As I'm using ballistic weapons, even the grenadiers were stretched at the time.
I'm fairly sure that if the aliens had been slightly more aggressive, I'd have been overrun.