That would explain the overloaded X-phasers.
"Sir, Enterprise redesigned, increases the main phasers by channeling it through the main engines. When the engines went into Anti-Matter Imbalance, phasers were automatically cut off."
Now, I remember in the novel Kirk actually ordered the phasers back to the way they were, and I think Scotty rigged it so they could function either way. (hence overload/normal) And I think an unofficial source quoted, or maybe it was Star Trek: The Magazine, that quoted some official off-screen source, that the phasers were increased by 50%.
One thing I'm kind of curious about though, in the OP Shiplist, I've seen X Cruisers, X- Destroyers, and X-Frigates. Did they try to refit the BattleCruisers and Light Cruisers with X-tech, or did they leave them to languish?