Good point about the use of Stargates. But the armoured Borg drones are kind of bright by being hive-minded and adaptable. The Jaffa are, well, no offense, Jaffa. On the verge of brain-washed, not encouraged to think and basically cannon-fodder. We can assume the Borg would adapt to staff weapon blasts within about 5 minutes: so a mass onslaught battle, which seems to be the way that Goa'uld typically do battle against each other, is going to go nowhere fast for the Jaffa. But the Goa'uld will be able to run away, far and fast, through the gate. Maybe come up with a bio-weapon?
The Kull warriors - interesting: again their weapons would be ineffective in a few minutes, but their own armour... it might take the Borg a while to adapt to that. But with no weapons, what use would the Kull be...