You know, some of us actually like the "made-up" SFU-native stuff that is not directly tied to the TV show; if all there had been for the setting was the initial range of TV-based material written up 30-odd years ago, there arguably wouldn't be a Star Fleet Universe still around to enjoy, or at least not anything close to the extent we have on hand today.
I for one picked up an interest in the seting precisely because of one such "home-grown" empire (the Inter-Stellar Concordium, which I first saw in SFC2 for the PC), and the range of new empires and settings play a much larger part in keeping me invested than the narrow band of "TV empires" do.
But then, given how annoying I can get with things on other SFU-related boards, I wonder if anyone else thinks that is such a good thing...
In terms of escorts, it's worth noting that in Federation Commander, a range of war cruiser excorts were published not so long ago in Booster Pack #92; and more escorts of the same type will appear this summer as part of the FC: Reinforcements Attack module release. As far as FC is concerned these escorts in particular do have Aegis, but are not tied to carrier operations the way they are in the Alpha Octant in SFB. (Although, it is akin to how SFB treats escorts over in the Omega Octant, where they are by no means wedded to carrier operations "historically".)
I would imagine those units being on the table for gradual transition to ACtA:SF as time goes on.
And in terms of variations between different types of direct-fire and seeking weapons used by different empires, there is a lot in the SFU; especially once you get out into the more distant settings. The original batch of TV empires were developed at the very beginning, and were the first to see their particular types of weapon combinations put together; it was only as the game progressed, and more fleets (and regions of space) were added in, that things could expand in new directions.
If you look over at ACtA:NA, the upcoming Vau will no doubt be dramatically different in terms of how their alien technology works compared to the various human fleets we've seen so far; but in order to get there, the core book had to show the five Royal House fleets as the baseline against which the more esoteric fleets can be judged.
Similarly, before the likes of the Andromedans are looked at (to say nothing of some of the truly alien empires beyond the Alpha Octant; if Mongoose ever decides to do anything with them, that is) the same kind of initial setup needed to be established here.
In short, this is by no means all that there is... so long as you're willing to give the "made-up" SFU-native material a fair look.