Actually I think that there is a moment where the borg do indeed become unstoppable.
It was a while ago... on SOA Trinity.... my friend was playing Borg (I so wish I had never show him , although that would likely have been only a temporarly solution.) and myself Federation.
We were allied against 4 hard AIs being Klingon, Romulan, Federation and Dominion.
It was a large map and so our steamroll was not very fast.
Everything was halfway fun.... until he lost connection.... making himself an enemy to me.
At this time... he had a fleet of
I tried to attack it.... my fleet died instantly.
As he had been doing most of the killing, it was not overly difficult to convince 3 of 4 Ais to ally with me.
Not that it made any difference, mind you.
Now matter how large of a fleet we jumped in.... half of it died within seconds, the other half was assimilated.
As capital/Elite ships are assimilated, too.... it quicky becomes unsolvable.
16 cubes "might" be winnable by 9 to 1 odds (with maxed out fleet supply) but 16 cubes + 20 Level 6+ Sovereigns and similar nasty stuff.... forget it.
While I respect the opinion of the creators of this - awesome - mod, I think that it would be a good idea to put the Elite Assimilator on a poor combat ship with low hull and armor (in comparsion to Borg).
It is quite impossible to fight an enemy that takes the best of your assets (high level capitalships) and uses them against you.
My friend ceased playing when I did forbid the usage of Borg.
I guess power makes addicted.
Imho there are more or less 2 versions of SOA. One normal version without Borg..... and the one with Borg.
The moment a borg player enters the field, you may as well set teams. Otherwise you risk getting eradicated in time.
And last but not least.... keep the Borg playable for Sins of a Solar Empire 2...... sometimes people have a bad day in real life.... and then few things beat going on warpath with as lumbering tactical cube.