However, there are particular advantages inherent in having no computer making these constant vector adjustments, not to mention there are certain flight maneuvers also, which can be performed more easily with no flight assistance engaged. A word of warning however! To go with these 'advantages', there are also disadvantages, most obvious is the lack of any rotational damping for ship orientation. This basically means any input initiated by the pilot of Pitch/Roll/or Yaw, has to be countered with its opposite to stop the rotation. In a nutshell, in actual practice the pilot him or herself instead is doing the job of the computer and that these inputs/counters are needed more or less constantly. A good experienced FA Off pilot eventually realises less is more, but still these counters are consistently needed despite them being small, tiny inputs, none the less.
That covers ship orientation, but ship momentum/direction/vector has to be adjusted by the pilot also. Again, with flight assist engaged, the computer is using ship thrusters to keep your current vector true and steady, and if a pitch or yaw is initiated (i.e.: you're asking the ship to change its vector) the ship flies in a steady arc/turn depending on how much pitch or yaw you've applied. With Flight Assist engaged and if the pilot requests a steady pitch (up or down), or yaw (left or right), the computer adds the relevant vertical/lateral thruster(s) so the ship's vector turns in relation to the amount of pitch and/or yaw you've applied, (otherwise all the pitch/yaw would do would simply rotate the ship's orientation). So with this in mind, with flight assist off, the pilot has to input the relative thruster(s) combined with the pitch or yaw, so the same steady turn/vector change can be achieved.
So far this all sounds like a disadvantage, and you're right, however, as mentioned certain maneuvers can be achieved with greater ease with no flight assistance, most useful being rotating against your current vector to the point you are facing backwards (180 deg) and still travelling on your existing vector. This can be achieved with FA On with the correct sequence of pitch and thrusters but would never be as easy as it is with FA Off. Many variations along this theme can be achieved more easily with no flight assistance, strafing a target at 90 deg to your current vector and all the angles in between. Like I say, all this can be accomplished with assist On, simply not as effortlessly.
The one main advantage with no flight assistance which has a considerable benefit especially when using Silent Running for example, is with this very fact of the Newtonian flight mechanic which has the advantage of generating considerably less heat from your ship, as constant throttle is not required for constant velocity. In the real world of Elite, as all radar uses ship heat signature to resolve a target blip on radar, even with the thrusters module still engaged in modules (still turned On), heat generation will not climb as quickly compared to when flying with assist On. After any initial momentum has been achieved, one can in essence drift on a current vector with zero throttle, dramatically reducing the amount of heat generated by your ship's engines. This may not sound like a huge benefit but it certainly is a gain towards reducing your ship's heat signature. The normal procedure to reduce ship heat is to turn specific modules off so the ship's power plant has less to do, but with engines specifically, and particularly how all ship's engines use approximately 30% of your available energy supply, reducing the load on ship thrusters has a noticeable effect on heat generation. If then additional modules are also switched off, will increase the effectiveness and longevity further still each time Silent Running is used, compared with flying with Assist On.
Some may say, after these pros & cons described, still it sounds like Flight Assist Off is more of a hindrance than a benefit, and even from those who use FA Off exclusively, they each say using FA Off is purely personal preference, and on the whole the disadvantages out way the advantages, they simply continue to pilot this way for the pure pleasure and challenge one gets from flying with no flight assistance, it certainly is addictive. However, those who use a combination of both, who toggle between FA On & Off, are the ones to be feared the most in combat, especially those who can continue the ships behaviour seamlessly when toggling between the two modes.