I have tried turning off the flight assist mode and it just causes me to go into a roll, i counter it and i go into a roll again....so i keep the thing on, if its something i have to turn off to do anything, i will move onto something else....the only time when i don't have a problem is when they are targeting someone else, which kinda defeats the purpose of it.
Yes, it is very awkward to fly with FA off, that's why I only ever use it for about 5 seconds at the very most. I only use it when the target is flying by me or out-turning me so that I can get him centred in my sights, turn FA back on again and fly normally.
Flick it off, pull back hard (it'll inevitably start rolling a bit at this stage, so I need to keep nudging the stick left and right a bit to counter, rudder seems to help too, weirdly). The more I practice the more stable the turn gets. For some reason, it only seems to work well for me if my initial speed is low (mid-low end of blue band). As soon as I turn FA off I also max throttles and you really can see a huge difference in turning speed. If I'm flying fast, FA off seems to be completely ineffective.
Best place to practise it is coming out from a station, as that gives you a frame of reference. Fly straight out a bit, then turn FA off and spin around and see how long it takes you to get the station centred ahead of you again.
Your other option, buy an Eagle or Vulture. I finally bought a Vulture last night and its turning speed is fantastic. Of course, with a Vulture AND FA Off, it's better again, it's insane how quickly it flips around and gets back on the target's tail.