Interesting theory, however the Odyssey was rammed in the engineering hull
and the debris bounced into the starboard nacelle.
Ah, I see. Couldn't quite remember if it was the neck or the engineering hull.
It might be the opposite, where a lower-powered propulsion system could make her fast and not tear herself apart (we've seen small, low-powered ships hit high warp speeds like the Delta Flyer.) The Defiant's extra powerful power systems OTOH comes with a penalty of overstressing the ship.
So the ship could pump more energy into its engines than the hull (or possibly the Structural Integrity Field) could handle?
Regarding phaser arrays:
I think of the trench in the middle of the array segments as the actual emitter. So the emitter is always as long as the whole array.
The phaser energy would be prepared in the prefire chambers below and then released into the trench, where a force field of some kind holds and transports the energy to the emission point where it is then released as a beam (maybe confined in an "annular confinement beam").
That way, the problem of the feasability (because of heat) of one array segment emitting the energy of the whole array would be avoided. Nob Akimoto's phaser arrays under the hull, because they only have single small emitters, would still have this problem, yet have some advantages of phaser arrays too.