Your example of the ships and rudders dates the tech, IMHO. A far future Enterprise should be like an X-65 compared to the Queen Elizabeth crossing the Atlantic... (IOW, going from rudders to no moving control surfaces plus flies above the water.)
Wait. SERIOUSLY? The X-65 is a
sailing yacht! Oh sure, there's nothing technologically dated about
sails! 
Also, you are absolutely missing the point here. The military ships are still using the tried-and-tested methods because they
work and they're
reliable, and a modern supercarrier is going to outpace a yacht. Maybe not in bursts, sure, but a
Nimitz or a
Gerald R Ford can sustain 30+ knots indefinitely until something breaks. The
Enterprise isn't a hotrod sailboat for rich people who have a couple of spare million to burn, or a tech demo for some academically inclined institution showing off its latest theories, it's a working starship that
has to be operational
as much as possible.
Well, I watched "Serene Squall" and the impulse thrusters were targeted and they disabled they were all in the warp nacelles (all 4 weapon hits targeted them). The damage spread back to the impulse exhausts on the back of the saucer. So it would seem that the producers of SNW don't think the impulse thrusters are exclusively on the back of the saucer or where they might have been assumed to be all these years... YMMV.
We were talking about the
Defiant specifically there, but sure, other starships have had impulse
reactors in other parts of their hulls apart from clustered where the engine exhausts are. There's even one highlighted on
Voyager's MSD. It's about power generation, and if we assume that impulse leverages subspace driver coils, that power could come from somewhere else.
Realistic means understandable with our current level of understanding. That, IMHO, dates it.
The ship's got faster-than-light engines, artificial gravity, and teleporters, but you're worried the
manoeuvring thrusters date it...
Curious, why should the Enterprise's technology be realistic given that by SNW's time they had the benefit of alien tech from all the other species they've made alliances with?
Why would alien technology be unrealistic? It's following the same laws of physics in the same universe. This isn't
Harry Potter.