I've never seen either, so I couldn't tell you, but I do know that they're going from an entirely different vein of sci-fi than that which I usually prefer. I'm much more in the Star Wars "slower-than-light lasers and massive explosions in space" school. 
Perhaps a better question is what have you seen of realistic sci-fi? Or are you assuming its bad because the very concept turns you off?
As an example, there is the school of thought that, ships need to be within spitting distance of one-another to make for an interesting battle. But then JMS made the battle of Gorash 7 in B5 where the Narn and Shadow ships are never within visual range (save the fighters) but the battle is still very entertaining. He then of course, proceeded to completely ignore the fact that he could do that sort of battle and went back to everything within spitting distance.
Even realistic sci-fi can be done well and interesting. The appeal factor of a given story is the story itself, and how it's presented, not whether or not fighters fly like WW2 craft or like they should in a zero-g environment. The very idea of realistic sci fi might be boring, but then again, having a ship get hit by a virtual shotgun blast of metal flying at relativistic speeds can be very entertaining if presented in a smart way. Some genres, like Batteletech for example are pretty realistic save for the theoretical use of the hyperspace jump. But most insystem travel to any area of interest is measured in weeks at most, and then when the battle is joined the ships are either fighting at the jump point itself or near the planet of interest so you get a pseudo-realistic setting with the potential to have somewhat entertaining battles. Similar in many ways to Freespace save the lack of in-system jumps.
I've read some CBT books, played MW4 and read pages off sarna.net. TBH, CBT is utterly unrealistic. Consider a modern MBT in the likes of Leopard 2, Challenger 2 and M1A2. Those tanks weigh in the range of 60-70 tonnes. Let's say we extrapolate such designs of such a weight class of armoured vehicles into the 30th century.
For a mech of that weight class, we are talking about Mad Dog to Warhammer. Those mechs are far larger in volume and surface area than tanks of the equivalent weight, which will, by real physics, given them paper thin armour compared to the tanks. Yet we see mechs being the king of the battlefield.
If we apply the same materials and technology onto armoured vehicles, they would be turning those fancy mechs into scrap metal with rail guns firing fin stabilized "sabot" shots while those melon shaped gauss rounds be bouncing off the glacial armour of tanks.
Of course, such a rational analysis would turn a geeky "cool" game with big shiny mechs into a dry military simulation like Harpoon.
Another thing, the rate of scientific advance is morbidly slow. While the IS states were blasting each other back to the stone age, the Kerensky formed clans should have leapfrogged in terms of technology (especially given their interest in warfare) to the stage that they should have
melted any IS army they touch, instead of facing the battlefield reverses as they did (guerrilla actions aside). The clans even lose the Trial of Refusal on the invasion of the IS and the IS forces didn't even have access to Clan tech.
Even after the arrival of the clans and temporary reformation of the Star League, the IS states with their vast amount of manpower, still couldn't reverse engineer clan tech and out compete the Clans in terms of tech. The FC/FS even developed their "black boxes" prior to the 4th Succession War and never took them further technologically or use them more widely. Instead, they relied (post 4th Succession War) on ComStar for communications, and the ComStar neutrality pledge is not worth the breath used to speak it, makes no military sense. The term "secure communications" does not seem exist in the CBT universe. It's like the US military using Nokia phones and a Nokia operated network for their secure communications.
I think I'll just stop here.
