The thing about the old X-wing and TIE Fighter sims that separates them from the rest of the pack (for one example, the Rogue Squadron series), is that they are suppose to be simulators. Being such, as a rule of simulators they are expected to accurately and faithfully simulate whatever subject they are based on. For a simulator to not follow this simple rule is a major "no, no" because it pretty much defeats the purpose of a game being a simulator. That's not to say it can't still be a great game in spite of this problem (which the X-wing/TIE sims definately were).
The drawback to this situation, is that they have become so extremely popular, that people have become much more familiar with the technical info within them than actual official LFL material and canon. In turn, people take the tech specs from the games (believing the info provided in them to be correct, seeing as how they are suppose to be simulators) and using them as a reference point. The Rogue Squadron games are allowed much more leniency because they simply are just arcade flight shooters rather than full fledged flight simulators. That being said, there are quite a few things I wish Factor 5 had done differently. lol 
Even though Star Wars is a fictitious source, it was an already well established franchise and had quite a bit of detailed official LFL technical material released before the X-wing/TIE sims arrived (as opposed to an original fictitious flight simulator like Freespace). Larry Holland, for whatever reason, didn't adhere to the already established technical info when developing the X-wing & TIE sims (Lord knows why).
Regarding the "The (New) Essential Guide To..." manuals, there are A LOT of things that are inconsistent not only with official 1st party LFL material and the films, but also with each other and all the secondary and tertiary EU they outline. In addition, the researchers and writers for these books seemingly didn't use any logic, common sense or deductive reasoning when detailing their material. Some info out right flew in the face of official 1st party LFL material. I could give a few very good examples if I can dig them out of my boxes, scan them into my PC and upload them. That would be a real pain in the neck, though, and I don't have a scanner... yet. 
Unfortunately, this is the problem when you have such a longstanding and popular franchise such as Star Wars. For 30 years now, it has constantly been added to and "evolving" from the works of many, many contributing sources (comic book/novel authors, video/card game developers, etc.). You get info that's been created by authors and developers who are working off of someone else's material, and creating their own contributions to the franchise through they're own personal impressions, opinions and interpretations regardless if it's accurate or in sync with the original source (George Lucas being the ultimate benchmark, obviously). Essentially, it all comes down to money. Star Wars is a very lucrative brand name, and by constantly adding and expanding it, they keep they business going and they make lots of money. Unfortunately, inconsistencies and contradictions to our franchise through EU material is just collateral damage. All the more reason that if you are a HUGE fan of Star Wars technical material and lore (which it looks like almost everyone here is) it's important to know the level of precedence/priority regarding Star Wars canon and material. Obviously LFL material is the #1 source and anything that contradicts it shouldn't be taken as canon.
Good Lord! This post turned out to be much longer than I intended. lol
Sorry, guys. I wasn't trying to give a lecture. I hope you guys still check it out, though. It's at least informative. *quickly throws clothes on and burns rubber to work*
Artificial intelligence is no match for natural stupidity.