And for the purpose of this set of rules what is Traveller is defined as the set of weapons, tech, gear, world generation, and starship creation similar to what the majority of Traveller edition featured. For example Jump Drive are Jump Drive in most editions of Traveller. The base stats for worlds are largely compatible from edition to edition. Traveller features guns and bullets more than beams and lasers.
Which I think really summarizes the question.
"What is Traveller"
What makes, for example, TNE "Traveller" vs T2K and DC, with the same mechanics.
Outside of the Imperium, with the Vilani, and other Alien races.
Is it simply the Jump drive? Is that really the distinguishing characteristic of Traveller?
For me, it's the Hard Tech of it, the Jump Drive, and the trade system. I think FFW is as close as we're going to get to view of high level operations in a Jump drive based universe. I would like to have more detail on wilderness refueling, and some day run some tactical attacks on a gas giant to better understand that battle space, since I think that is key to understanding the operational game. I'd like to see the fleet train better documented, some supply guidelines (I know there have been some comparative stabs at that in the recent past). Better understanding of the economy would be good too. In the end, I still feel that battle is extraordinarily expense, very, very lethal, and clashing empires will stand still very quickly as their fleets are destroyed and become too costly to risk and field. I think what happened in the Rebellion is pretty "realistic" in the abstract, all told.
Miller can claim it's "Space Opera" all he wants, but if so, he sure let Chadwick overshadow the bulk of the design elements, shrouding that aspect of the game. Perhaps politically and culturally it's more Space Opera-ish.
The imperium and politics are really a far second for me. I've never been much of a Canonista in that regard.