As has been stated over and over.
Manually trimming your plane will not make it turn faster"
Yes and no. In few cases it can help tighten turn radius (at certain speeds), better control response (stick push at slow speeds, torque control, etc), and in some cases make airplane do what suppose not to be possible.
In AH1 combat trim was nearly instantaneous, it made no sense, except at higher speeds for select planes, adjusting trim manually.
AH2 is different. Combat trim is slower. Furthermore, in some cases it is used to simulate control heaviness at high speeds for some rides and with manual trim you get performance which historically wasn't there.
That said, manual trim won't make you fly better until you're good enough to squeeze maximum out of your plane. Even then, you won't have time to trim plane during combat (at least in most cases). Usually you'd adjust your trim before entering fight for specific speed range. That would mean, your ride might not perform best in all regimes.
So, in short, leave the manual trim for now, unless you are looking for that extra immersion.