That fan model was done before we had photos of the butt end of the original, so it misses out on the giant round impulse engine things. If we acknowledge those, it probably makes sense to interpret the E-B saucer boxes as something other than impulse engines. They'd make for pretty good shuttlebays, now wouldn't they?
Also, I'd like to see that ship oriented the other way 'round, with the third nacelle at the bottom. The original model is symmetric, and actually has its Starfleet arrowheads stenciled on "upside down", supporting the third-nacelle-down interpretation.
Now remove the third nacelle and you get a pretty decent-looking ship (say, the Excelsior
family equivalent to those light cruisers of Starfleet Battles fame)... Perhaps the third engine is an optional extra? A torpedo pod might go in its place in other variants of this ship type. No other feature on the ship would seem to be applicable as a forward-firing torpedo launcher, after all.