What about the Merchantman freighter?
From what I can see this vessel had two long structures port and starboard, probably paired warp engines of a somewhat different configuration.
Alright, please allow me to take the debate to a different point of view.
It has been observed (correctly, IMHO) that there are design elements in Matt Jefferies' TOS Enterprise that most cleverly create a familiarity with the design on the subconscious level (I prefer "unconscious" according to Professor Freud) namely for the female and male design "elements" (e.g. warp nacelles "caps", lower sensor "dome").
If I continue these human body allusions, a pair of warp nacelles carries the allusion to a pair of walking legs, which perfectly fits the context as their prime function is to enable movement, too.
However, a single warp nacelle design no longer carries this ambiguous allusion but limits itself to just the one "male" design element.
Considering the size and proportions of the single nacelle in nuTrek I can't help the suspicion that someone tried to compensate for...okay, I better stop before I get a "R" rating or worse from the moderator.

Deanna Troi once said "sometimes a cigar, is just a cigar [and not a Freudian symbol]". In the case of the single warp nacelle design, however, I'm honestly not that sure.
Bob