Hmm... something that I thought right away when you guys were talking about how bad the Drinniol revolt was vs. the Nahk vs. the S'pht was that perhaps it didn't deal with raw damage, but with efficiency.
Here's a plausible scenario:
The major Jjaro outpost had only a small number of ships because -- despite being major -- it was a place of technology, and the tech the Pfhor stole could be replicated more easily on their own planets through mass production, et cetera. So very few ships there. There was no precedent of the Drinniol rebellion, so the Pfhor didn't know how to handle it. They were wiped out within (say) half an hour, and the Hulks swiped the few ships at the outpost and were traveling to the planets (if there were any) or simply consolidating their forces (if there weren't), reasoning that taking their rebellion one system at a time was a reasonable thing to do. Then some few remaining Pfhor holed up in a command center or a warehouse or something found a Trih Xeem and used it for the first time. With no amazing AIs to come to their rescue, the Drinniol of the outpost and every other living being within the system became lightly-roasted space dust. Since this was the first use of the Trih Xeem, the Drinniol didn't know that they shoulda escaped when they had the chance and so became said space dust.
Now, my main point is the "half an hour" bit: within 30 minutes or fewer, a Pfhor-controlled system was completely lost, and not to things like the *MAGIC* of orbital bombardment or space combat. The place was taken, not destroyed. The Pfhor that activated the Trih Xeem knew that if these enhanced Drinniol got out into his empire, his empire would be holding the short end of the stick, so he hit the only panic button he could find.
The Nahk rebellion, on the other hand, may have been more widespread, but perhaps far less effective overall. Maybe weeks or months for each planet, or longer. Similarly, the S'pht may have gutted the computers of the Pfhor, but they were still able to mount a sustained, if losing, defense/offense.
Just some ideas.
Lunair