Mr. Laser Beam wrote:
IIRC, all of the Excelsior-class ships we have ever seen in Trek have had the same nacelle design, at least in terms of outward appearance. Yet they are obviously not transwarp.
Because it was the same model. And the only Excelsior-class vessels we've seen (aside from 1701-B) were in the 24th century, when all ships were transwarp (or at least 100 years advanced in tech, whatever you wish to call it).
So, this really says nothing about Excelsior's capabilities (or moreover, lack thereof).